This is the B4-2 Standard Model Rocket Engines/Motors from Estes.
Suitable for Ages 10 & Older with Adult Supervision for Those Under 12.
Three B4-2 Engines
Four Igniter Plugs
Single stage engine
Standard engine designed for flights in rockets weighing less
than 4 ounces, including the engine
Engines tested and certified by the NAR
Easy to use and comes with clear instructions
Length: 2.75" (7cm)
Diameter: .69" (18mm)
Adult Supervision for Children Under 12