This is the F23-4FJ 29mm x 83mm Single Use Econojet Model Rocket Motor from AeroTech Consumer Aerospace. FEATURES: Black Max- Provides the high visibility tracking of dense black exhaust Motors give your models lower acceleration and longer powered flight than White Lightning or Blue Thunder motors of the same total impulse Provides slightly higher acceleration than White Lightning Propellant Instruction sheet included INCLUDES: One F23-4FJ 29mm x 83mm Single Use Econojet Model Rocket Motor SPECS: Propellant type- Black Max Dimensions: 1.125" x 3.283" (29mm x 83mm) Motor weight- 3.0oz. (84g) Propellant weight - 1.2oz. (33g) Maximum recommended lift-off weight: 22oz. (620g) tlh 2/25/11