The type that sded and Tim recommend we used to call automatic strippers and we required on some job sites so you would not cut a small ring around the copper when stripping wire with the style that Larry is showing. The simple style of stripper in Larry's post is perfectly sized for solid wire and even though it has sizes for solid and stranded listed the stranded don't fit as perfectly so damage to the wire at the critical spot where the crimp goes is easy to do. The automatic style in good working order reliably strips the wire without damage.