Yeah Racing Aluminum Nos Nitrous Oxide Balance Weight Bottle 23g For 1/10 RC Blue
The description:

This is the Yeah Racing Nos Nitrous Oxide Balance Weight Bottle 23g for 1/10 RC Blue. This bottle can help refine the balance of your chassis while giving it a better look. Yeah Racing exquisitely uses the highest quality material combined with precise CNC cutting to manufacture this balance weight bottle.