This Model Rocket Accessory Package is An Engine Mount Kit for "D" and "E" Engines by Estes. FEATURES: With the parts in this accessory kit, you will be able to construct two D and/or E engine mounts. An adapter is included to allow you to fly D engines in the E engine mount. The spacer ring provided allows you to "field" convert an E engine mount to use D engines. You can build these mounts to fit BT-55, BT-60, or BT-80 body tubes. There are extra parts, so save them for future use. Two different size engine hooks (one fits D engines and the other fits E engines). The engine mount tubes provided with this kit are heavy duty and thus thicker walled. Fully detailed assembly instructions with illustrations. INCLUDES: Two Engine Mount Tubes Two Engine Retainer Rings Two Centering Ring Sheets One Spacer Ring Two Engine Blocks Four Centering Rings Two "E" Engine Hooks One "D" Engine Hook REQUIRES: Hobby Knife Sandpaper CA Glue, Wood Glue, or 5 Minute Epoxy Pencil Ruler