The 
Airtech Studios Tanker Battery Extension (TBEU™)
 is an upgrade designed to increase the battery compartment space for KWA PDW-style airsoft rifles. It solves the common issue of cramped internal space that can lead to wire damage or limited gameplay time due to small battery capacities. 
 
 
Key Features & Benefits
Increased Capacity: Provides approximately 60-70% more space, allowing for the use of larger LiPo batteries to ensure longer field time.
Component Protection: Relieves stress on the MOSFET, fuse, and wiring by preventing overbending and potential overheating.
Stock Stability: Once installed, it eliminates the "rattle" or wobble common in PDW butt-stocks by locking down the two metal rails.
Durability: Constructed from impact-resistant, reinforced nylon polymer that can withstand BB impacts and rough handling.