With competition-level LiPo batteries mostly available with either 4mm or 5mm plugs, mix and matching different brands with different sizes plugs can be a real challenge. Arrowmax had come to the rescue by introducing a 5mm to 4mm down-sizing jacket. Different with most other similar products on the market now, the jacket works by inserting into the 5mm plug on the LiPo and effectively converting it to 4mm. No soldering and very convenient to move from pack to pack. You can maintain your charging cable and ESC connection with the same 4mm plugs and still being able to use LiPo with 5mm conncetion. They come 24K gold plated for maximum conductivity. Available now.