What thumb release is mike Fitzgerald useing and do you have to change your peep height if you switch to a hand held release. Thanks you guys are the best

Mike is shooting a Hot Shot Tempest - made famous by the one and only Mr. Stan "Give me a second" Potts.

As for your anchor point and peep sight, in my experience, yes, it will change between a wrist-strap/index finger release and a handheld/thumb-trigger.