Battery bay for Zephyr II similar to the plywood one used by TBS to hold two 4s 3300mah batteries (Turnigy or Zippy compact should work) in parallel. Also has slots for velcro straps. I can provided ipt or stp files if neededIf you're going to have a fpv cam at the front, make sure to carve out a slot in the side from the electronics bay to the front and place the camera cable first. Once the Battery Bay is glued, the side will be inaccessible. Carve out a slot for the velcro straps to slide through in between the foam and the bay then glue in the battery bay. (I used gorilla glue)