With the exception of the fiber head and battery/charger combo, FiberFlies does not sell replacement parts like the end cap. Sending out an end cap would be to replace someone's already existing end cap that was defective, which complies with our warranty. However, if the end cap is lost/stolen/misplaced, that is on the customer, and we cannot pull product from replacement stock for a customer-faulted issue. You'd have to buy a new rig. This is the common stance for many retail products out there.