Hoppes gun cleaning kit clamshell is made of durable polypropylene. It includes no. 9 solvent, lubricating oil, patches, rod knob, slotted ends and brush to keep your gun clean and shooting properly all year round. Hoppes gun cleaning kit clamshell is made of durable polypropylene. It includes no. 9 solvent, lubricating oil, patches, rod knob, slotted ends and brush to keep your gun clean and shooting properly all year round.