While replacing the gears in transfercase servo motor I lost the circlip (a.k.a. retaining ring).

I measured the shaft on which the gear goes and it appears to be 3/8" in the groove.

I looked up on Amazon and it seems that there are no genuine BMW circlips available. So I plan to go with aftermarket circlip set like this one - https://www.amazon.com/Hilitchi-Stai...gateway&sr=8-5

Anyone has recommendations what parameters to look for in the circlip?