8 part numbers tracked · 15 in stock now · prices updated
He12 is WD/HGST's name for the HUH721212-series 12TB helium-sealed enterprise hard drive - the same base part number WD's current site also sells as the "Ultrastar DC HC520". We track 8 distinct HUH721212 part numbers across SAS and SATA, 5 of them 4Kn or 512e SAS and 3 SATA 512e, with 15 in stock right now. It reaches buyers almost entirely as an enterprise pull: He12/HC520 currently accounts for roughly 55% of the recertified 12TB listings we track.
"He12" and "HUH721212" are not one product - they are a base part number that WD and HGST issued across at least 8 suffixes, split between SAS and SATA interfaces and, on the SAS side, between two sector formats that are not interchangeable. Every part number below is one we hold a dedicated reference page for, decoded segment by segment from WD's published Ultrastar interface-suffix documentation - not a guess at what the trailing letters mean.
| Part number | Interface | Sector format | Family label in our catalogue | |
|---|---|---|---|---|
| HUH721212AL4200 | SAS-12G | - | Ultrastar DC | decode → |
| HUH721212AL4201 | SAS-12G | - | Ultrastar He12 | decode → |
| HUH721212AL5200 | SAS-12G | - | Ultrastar HC520 | decode → |
| HUH721212AL5204 | SAS-12G | - | Ultrastar HC520 | decode → |
| HUH721212AL5205 | SAS-12G | - | Ultrastar HC520 | decode → |
| HUH721212ALE600 | SATA-6G | 512e | Ultrastar HC520 | decode → |
| HUH721212ALE601 | SATA-6G | 512e | Ultrastar HC520 | decode → |
| HUH721212ALE604 | SATA-6G | 512e | Ultrastar HC520 | decode → |
Amber sector format = 4Kn, the one that will not drop into a 512e array. Every row links to its own part-number page for the full segment decode, sibling variants and live offers.
We tried to source WD's own account of this before writing anything here. WD's PDF document library, the Wayback Machine and HGST's legacy site were all unreachable to a rendering-free fetch, and WD's current live product pages are JavaScript applications that return no body content without a browser - so we could not confirm or deny, from a WD source, whether "He12" and "HC520" name the same generation or two different ones. What we did verify live on 2026-09-12: WD's current site has a real product page for the "12TB Ultrastar DC HC520" and no page at all for a dedicated He-series line - that URL 404s. Neither name appears alongside the other on any page we could read.
What we can show instead is our own data, which is directly verifiable: the same exact part number, HUH721212ALE600, appears in different listings in our catalogue labelled both "Ultrastar He12" and "Ultrastar HC520" - the table above lists the family label attached to each part number as we hold it. We read that as evidence the two names circulate for the same hardware in the market this site tracks, not as proof of what WD intends by either name. If you are searching by part number rather than by name, the decode table above is the same answer either way.
He12/HC520 is not a marginal contributor to 12TB refurbished supply - it is close to being the supply. Of the 20 recertified 12TB listings we track right now, 11 (about 55%) are HUH721212-series drives. That is why a buyer comparing new-versus-recertified at 12TB is, more often than not, specifically comparing new-versus-recertified He12.
Two different measurements, on purpose. The shelf spread compares whatever is currently cheapest on each side, which can be two different products; the matched figure compares each model against its own price in the other condition and is the one worth trusting when the model count behind it is not tiny. Given how much of 12TB recertified supply is specifically He12/HC520, the site-wide 12TB figures on the right are close to a He12 figure already - the full breakdown, listings and supply context for the whole capacity live at Recertified 12TB drives.
11 at/near low · 3 typical · 1 elevated
| Model | Capacity | Recording | Price | Verdict | $/TB | |
|---|---|---|---|---|---|---|
| HUH721212ALE604 Refurbished | 12TB | CMR | $330 | AT/NEAR LOW since 2026-08-14 | $27.50 | Buy |
| HUH721212ALE604 Refurbished | 12TB | CMR | $330 | AT/NEAR LOW since 2026-08-14 | $27.50 | Buy |
| HUH721212ALE601 New | 12TB | CMR | $330 | AT/NEAR LOW since 2026-08-14 | $27.50 | Buy |
| HUH721212ALE601 Refurbished | 12TB | CMR | $340 | AT/NEAR LOW since 2026-08-14 | $28.33 | Buy |
| HUH721212AL4200 Refurbished | 12TB | CMR | $348 | AT/NEAR LOW since 2026-08-14 | $29.00 | Buy |
| HUH721212ALE600 Refurbished | 12TB | CMR | $350 | AT/NEAR LOW since 2026-08-14 | $29.17 | Buy |
| HUH721212ALE600 Refurbished | 12TB | CMR | $350 | AT/NEAR LOW since 2026-08-14 | $29.17 | Buy |
| HUH721212ALE604 Refurbished | 12TB | CMR | $360 | AT/NEAR LOW since 2026-08-14 | $30.00 | Buy |
| HUH721212AL4201 Refurbished | 12TB | CMR | $400 | AT/NEAR LOW since 2026-08-19 | $33.33 | Buy |
| HUH721212AL4201 New | 12TB | CMR | $534 | AT/NEAR LOW since 2026-08-14 | $44.54 | Buy |
| HUH721212ALE600 New | 12TB | CMR | $599 | AT/NEAR LOW since 2026-08-14 | $49.92 | Buy |
| HUH721212ALE604 Refurbished | 12TB | CMR | $340 | TYPICAL since 2026-08-14 | $28.33 | Buy |
| HUH721212AL4200 Refurbished | 12TB | CMR | $384 | TYPICAL since 2026-08-14 | $31.96 | Buy |
| HUH721212AL4200 New | 12TB | CMR | $655 | TYPICAL since 2026-08-14 | $54.62 | Buy |
| HUH721212AL5204 Refurbished | 12TB | CMR | $354 | ELEVATED since 2026-08-14 | $29.50 | Buy |
Verdicts are computed from our own daily snapshots, always against the same drive's own record and never against a manufacturer list price. The only price shown on this page is the current one, with the time we last checked it — we publish the verdict as a label rather than printing past prices. Out-of-stock drives are excluded entirely, and the date beside each badge tells you how long we have been watching that drive.
He12/HC520 is a nearline enterprise platform, not a NAS-branded line, so vendor compatibility claims for it come from the same registries the rest of the site uses rather than a NAS-maker's own marketing for the drive.
It also shows up outside the NAS-compatibility registries: on every NAS drive-fill calculator page on this site, the "enterprise" tier - the cheapest current SATA CMR drive from a named enterprise line - is, at today's prices, a He12/HC520 listing. That tier picks one drive site-wide by live cost per terabyte rather than per model, so which exact part number holds it moves with the market; it currently does.
Computed, not asserted: right now the cheapest current-generation Ultrastar at 14TB or above is $24.29/TB, cheaper per terabyte than the cheapest He12/HC520 we track at $27.50/TB. When that happens, the honest answer is that a newer, larger drive is the better value today - a result the price ladder can produce and this page will not talk around.
The digit before the interface letters is what changes: AL4200 uses the AL4 code, which WD's own Ultrastar interface-suffix documentation defines as SAS 12Gb/s with 4Kn (4K native) sector format, while AL5200 uses AL5, defined as SAS 12Gb/s with 512e. Both are 12TB SAS drives from the same HUH721212 base part number - the sector format is the whole difference, and it is not cosmetic: a 4Kn drive will not drop into an array or controller expecting 512e. The PN variant table above carries this exact distinction for every part number in the cluster, not just these two.
Yes, per WD's own account of the technology (not something we tested). WD's published history of the HelioSeal platform states that a helium-filled enclosure is roughly seven times lighter than air, which it says creates less drag and turbulence as the platters spin - letting WD fit more, thinner platters into the same 3.5-inch body than an air-filled design could - and that the sealed enclosure also runs cooler and keeps out humidity. WD's account of the first commercial helium drive (2013) states it shipped with 50% more capacity than any air-filled hard drive at the time while using about three-quarters the power. Those are WD's own claims about the platform generally; we have not run a power or thermal test on any specific He12 unit ourselves, and this page makes no such claim.
We could not verify that from WD's own documentation, and we are not going to assert it. What we can show is what our own catalogue actually contains: the exact same part number, HUH721212ALE600, appears in different listings under both the “He12” and “HC520” names, and the naming split section above sets out exactly which part numbers carry which label in what we track. WD's current live site has a page for the HC520 at 12TB and no dedicated He-series page at all, so HC520 is the name WD currently uses in its own marketing - but that is a fact about WD's website today, not a documented statement that the two names refer to the same design.
That depends entirely on what your controller or backplane takes, not on any difference in the drive itself: nothing in what WD documents about the interface suffixes suggests the SAS and SATA variants differ in anything but the interface and its sector-format options. A SAS drive needs a SAS host bus adapter or backplane - it will not run from a motherboard SATA port - while a SATA drive will run on either a SATA port or a SAS controller. If your system already has one interface wired in, that answers the question before price does.
15 in stock at the moment this page was generated - 4 new and 11 recertified or used, across 8 distinct part numbers (5 SAS, 3 SATA). The live listings table above is that exact set, ranked by verdict then by cost per terabyte.