These buttons are very great. Probably top 3 in the market. However with being locked into those omicron switches vs having more options in mechanical keyboard switches that can be swapped out like Gamerfinger buttons I haven't looked back. Not even sanwa buttons
Go with 30mm unless you have leverless or a custom box. 30mm is the standard size for most fight sticks, although it’s still best to check the size to be sure.