These check cords are constructed of the same multi-filament polypropylene roping used in all of Mendota’s products. These long lines are UV coated to protect against decay and fading, and are gentle on the hands. These trainers and super cords are the professional's choice for training to come on command and retrieving to hand. Sizes:Obedience 20: 3/8″ x 20′ – BlackTrainer 30: 3/8″ x 30′ – OrangeTrainer 50: 3/8″ x 50′ – OrangePro Trainer 30: 1/2″ x 30′ – OrangeSuper Cord 30: 7/16" x 30' - Hi-Viz YellowSuper Cord 50: 7/16" x 50' - Hi-Viz Yellow