http://www.apogeerockets.com/Building_Supplies/Nose_Cones/Low_Mid_Power_Nose_Cones/66mm_TARC_Foam_Nose_Cone The BT-80 size (66mm diameter) foam nose cone for Team America Rocketry Competition are designed to add extra protection to the egg. They deform when they hit the ground, and yet will spring back to shape to be used again and again. They also have a core that you can use to install your altimeter.