Increase the power of your Sui-Side Mod with the Sui-Side Stacker! To use, simply unscrew your device’s copper battery cup and add it to the bottom of the stack section with a battery installed. Then add the additional battery into the top of the stacker and intall back onto the mod. Cover the stacker with the included new stacker bottom delrin cover. This will now give you the power of a two battery series device producing 8.4 volts. You must ensure that you have a great understanding of Ohms Law and battery safety before purchasing this device.