This is the Engine Mount Kit for "D" & "E" Engines from Estes. Suitable for Ages 10 & Older with Adult Supervision for Those Under 12. FEATURES: Heavy duty engine mounts for "D" and "E" engines Fits BT-55, BT-60 and/or BT-80 body tubes Fully detailed assembly instructions with illustrations INCLUDES: One "D" engine hook Two engine tubes Four AR5055 rings Two RA5060 rings Two RA5080 rings Two "E" engien hooks Two retainer rings 1 "D" engine spacer 2 engine blocks REQUIRES: Hobby knife (RMXR6909) Sandpaper COMMENTS: Due to small parts that could cause a choking hazard please keep away from children 3 years of age and younger For your safety and enjoyment, always follow the NAR Model Rocketry Safety Code while participating in any model rocketry activities kr6/21/01 ir/jl updated tlc 1/10/13