A bottle of 1000 rds .5g of LongBow heavy weight sniper grade Airsoft BBs.
BBs weigh different amounts, these BBs are .5 grams. Here is a chart of recommended BB weights for Fps measured with .2g
~480 FPS .36g
480-500 FPS .4g
500-540 FPS .43g
540-580 FPS .45g
580-630 FPS .5g
These are recommended weights for sniper rifles. The fps sometimes overlapps, when it does, you can use either bb weight for good performance. This chart does not necessarily apply to fully automatic rifles, you can find their chart on Valken BB pages.