This was designed by request from my friend Mike. He wanted something that would allow him to carry multiple USB cell phone backup batteries on his belt, which resulted in this model. This is designed to hold four semi-rounded backup batteries up to 26mm in diameter. For batteries smaller than that, they can be padded to fit using rubber bands. The belt loops have a few small bridges to make them easier to print with flexible filament while keeping them vertical. They can be easily cut and removed after printing.