Rainbow cogged vacuum belt R15364B.
This belt will only fit newer E2 power heads where the motor shaft if grooved and not threaded.
This belt is installed on the side of the brush roller.
7.9 mm wide. This belt has 4 grooves on the inside which line up with the motor shaft mentioned above.
Rainbow E2 models that use this belt began in being made in the middle of 2013.
