+1 on CT. It doesn't affect anything till you hit the on button. Other than that they are just a pair of grips. I have 3 on house and carry guns. Batteries last for MANY years, and they are as durable as a rock.
C/T is a very good quality product and the grip laser works well in a pinch. battery life on watch batteries is 5-7 years or 4 hours of use. they will dull out when continually held buy recouped when left alone for a while