Review on NBIKE Bar End Plugs: End Caps for Bicycle Handlebars - Mountain & Road Bikes, Various Colors, Easy Installation (1 Pair, No Logos) by Emanuel Frison

Plastic end cap fits most aluminum flat and cruise bars. Too big for carbon and too small for steel. The plug is made of medium-hard plastic with a small built-in hex nut. There is no locking plate, so over-tightening will destroy the connector and pull the nut out. Proper tightening is to finger tighten the short lever and then the long lever an additional 1/4 turn. A rigid lock is not enough and has nothing to do with expansion dowels for preloading a headset. The flat surfaces of the lid are tapered leaving a small gap for sand. The overall diameter of the cap is large enough to cover the pipe but not enough to close the handle ends. There are many resellers of the same type of cap and they are all pretty much the same. It was the lowest price I've ever bought. It's good to save you from an accident, but don't expect a finished look.