This design is SO much sturdier than the usual workstands designed to clamp the bike by the seat tube - makes is SO much easier to clean and work on the drivetrain, for example. For 12mm axles, you can buy an adapter for just £12 (made by Halo) which fits inside the 15mm one, alternatively you can buy the 12/15mm Park Tool set for another ~£60.
eBay