ST Racing Concepts STH85053GM Threaded Aluminum Rear Shock Set with Lower Caps and O-Ring Collars for The HPI Blitz and E-Firestorm (Gun Metal) Features threaded aluminum shock bodies with O-ring installed pre-load collars in which the O-ring secures your pre-load adjustments in place Features aluminum lower shock caps to keep the shock cartridge straight and flex free during suspension operation When used in combine with our heavy duty upper shock cap It provides the ultimate smoothness and durability in suspension for your HPI Blitz