The Efest Purple Series is an ideal battery choice for mechanical mods. It features an 18500 size with a 15A 1000mAh capacity in a button-top version.

Safety Notes:

Do not over-discharge/overcharge
Recharge empty batteries (resting voltage ~3.6V) promptly to avoid irreversible damage
Avoid short circuits, as they can release tremendous current
Never dispose of batteries in a fire
Safe chemistry LiMN reduces the risk of venting with flame or explosion. IMR-safe chemistry batteries do not include built-in protection circuitry, resulting in a slightly shorter battery length that fits most mods well. It is advised not to discharge the battery below 2.5V to ensure longevity.

IMR cells lack a built-in protection circuit and should not be discharged below 2.5 volts, as it can reduce cycle life and performance. The maximum charge voltage is 4.25 volts.