2.6" - 38mm (64.9 - 38mm) centering ring holds 38mm motor tube inside 2.6" airframe. 1/4"  plywood.
Fits into any 2.6" airframe including BT-80 tube. Works best with Rocketarium 38mm(T), PML phenolic 38mm Tube and LOC fiberglass 38mm motor tube. (41.8mm motor tube OD)
 - 41.85,  - 64.75mm,  6mm,  7g