With out it very hard to lock your thumb in. the thumb rest made it it possible to hold the firearm a lot steadier.
On the slide lock bar just ahead of the grip area, I drilled, and tapped the bar for a small bolt. I threaded it in, welded it, ground it smooth and enlarged the bolt head with weld, then rounded it smooth.... Now, I have a thumb operated slide lock ! Besides, I figured for the cost of the pistol, I couldn't possibly damage it! Works for me! Bill
And cheaper than buying it from the now-defunct Makarov_dot_com. Those SOB's never did send the CZ52 parts my buddy ordered a year ago....