The Killer Bee was an attempt at making a fast reed valve 049 engine from information that had been learned over the years of racing and competition. It had a tapered cylinder with SPI and lighter piston similar to the Tee Dee, a stronger balanced crankshaft and a new reed valve shape. They had a Yellow plastic needle valve. Later in 2002 Estes produced a Killer Bee that had none of these features but looked like the original Killer Bee except for the needle valve. Beware of fakes! Some unscrupulous people are producing fakes and selling them. Check to make sure the engine is the "real deal" before purchasing.