Plenty of happy reviews here:
http://www.civinfo.com/forum/tegiwa-imports/105838-rigid-collar-set-14.html
It's the risk you take, I'm only going off what several people have either told me or I read on build threads. I run with a few Tegiwa bits and the quality is OK but not perfect as to be expected for the budget. Except for their fog scoops, they're actually lush (just hoping the fit is perfect lol)
Tegiwa's design is slightly different as it's more of a washer with a tapered sleeve whereas spoon's locks the two together and is tapered on both sides.