You WILL be seen with this super bright tail light. 100+ hour run time per charge (flash mode)Quickly and easily mounted to seat post or frame.Set includes tail light, mounting rings, charger and 4400mA - 7.4V Li-ion Battery pack with an integrated protection circuit to prevent over-charging or over-discharging and to balance the charge between cells.These packs are built with cells from LG Chem, the battery supplier for the new Chevy Volt!