okay....good news!!! they will fit the KR8 shorty battery perfectly they will fit the 510 battery perfectly with care.. and they WILL fit a 510 manual battery! all you have to do is cut a little X over the switch before you apply your heat from the hair dryer. My ever helpful husband walked in while I was using the hair dryer to apply a skin to my 510 PT. He says....would you like me to get you my heat gun? ah....that would be a no....we are talking a device designed to apply the skin to airplane wings.