I believe they have more than one style that fits the G27. I got the Cozy Partner Model 53, which has the thumb snap. I didn’t think I liked it at first, but it has grown on me. They are very helpful if you give them a call and tell them what you have/want. Very comfortable inner lining.
BTW, here’s something you may not know about your G27, it’s 3 guns in one.
You can buy conversion barrels for it in 9mm and 357sig and all you need to
refit is buy a 9mm magazine, 357sig fits in the 40cal magazine. I keep 9mm in
mine pretty much permanently. It’s so much cheaper to shoot and less hard on
your hand.