This is a battery caddy attachment for the Pirl Charger. You can get the charger here: https://www.kickstarter.com/projects/pirl/the-ultimate-charger-for-power-users/ The files "pirlbracketcaddy1" and "pirlcaddycap.stl" fit this battery pack: "Turnigy 800mAh 3S 20C Lipo Pack". The files "pirlbracketcaddy2.stl" and "pirlcaddycap2.stl" fit these battery packs: "ZIPPY Compact 1000mAh 3S 25C Lipo Pack" and "Turnigy 1000mAh 3S 20C Lipo Pack"