The pitlock 4 piece skewer set is a coded high security protection device that is a direct replacement for the quick release skewers on frontrear wheels and seat posts and head set you will need a 14mm spanner to fit them you must carry the key and spanner with you whilst cycling to allow wheel removal for punctures etc can only be used on bikes with qr skewers and will not work with solid nutted axles set features front rear wheel seat post skewers 1 pits and 1 security code id