Scratches the surface and uncomfy for lefties - JP Enterprises Adjustable/Reversible Safety Selector Kit

So you have to tighten the screw very carefully to get the right "tightness", too tight and it will scratch the receiver and too loose the right switch will slip.

For lefties, the index finger is going to rest against the selector and it might feel uncomfortable if you are going for a precision pull.

Overall, very mixed feelings about this one. It's best for a non-precious rifle.