This is a cap designed to fit over the 5.5 mm bullet connectors. I use these caps to protect my LiPo batteries from shortcut durring storage or transport. If you are using ABS and your printer is not equiped with extruder fan I recommend you to print more caps at once. Small diameters made of ABS tends to shrink when You print too fast without cooling. I was printing these caps on Solidoodle 2. Layer height was 0.2mm.