2.1" (P) - 1.6" (P) (ID 54 mm - 38 mm) centering ring holds 38mm PHENOLIC motor tube inside 2.1" PHENOLIC Airframe. 1/4" plywood.
Fits into 2.1" Phenolic Airframe Only. Works best with PML and GLR phenolic, Hawk Mt and LOC fiberglass 38mm motor tube. (1.65" motor tube OD)

Please see previous item for same ring cut for different 38mm tubes.

- 1.657", - 2.156",  0.25"