Park tool fourth hand cable stretcher bt 2commonly referred to as a 4th hand the park tool cable stretcher pulls cables tight for adjustment of derailleurs and brakes it features one hand operation with a thumb lock to hold the cable tight while your hand is freed up to tighten pull up bolts and nutsa must for any shop home or professional thumb lock for one handed operation made from chrome plated heat treated steel cushion grips for comfortbuy park tool fourth hand cable stretcher from c