Built with two opposing magnets to hold the pliers open, the Mag Spring mechanism cannot fail, unlike conventional plier springs. The split ring nose on the 4 model opens rings from size 0 up, while the 18 cm pliers are ideally suited for size 35 rings. The cutter on both sizes cuts all line sizes. The pliers feature stainless steel jaws and co-molded grips. Only 18 cm pliers come with a molded plastic sheath. 15 cm model doesnt include a sheath.