The M1P5 with extension is new to the Avid Lyfe lineup. The M1P5 w/extension is a mechanical mod which will run up to 2 x 18650 batteries. The M1P5 Mod is precision machined with state-of-the-art CNC machines. WARNING: For advanced users only. Rebuild-able atomizers and mechanical mods require a basic knowledge of Ohm's law, battery amperage, electrical resistance, as well as experienced coil-building. Vape only within the safe limits of the battery you use. Build and use at your own risk. Axis Vapor is not responsible for misuse of product or user error.