scuoaCoolerMaster uses 6.25 space bars. The only nonstandard from CM is the Quickfire TK I believe. Everything else is standard. I own two CM QFRs, and their newest "Masterkeys" also have standard bottom rows.
Oatburner6.5u spacebar is needed for Corsair K60/K65/K70/K90/Strafe keyboards, but no custom keycap manufacturer is making such nonstandard size spacebars