In order to ensure compatibility we send out different sized belts based on what other products are ordered with the Complete Pulley System.
All of our belts are HTD 5M 15mm Wide, but the length varies based on the motor mount purchased along side of it.
If you purchase a Premium Motor Mount, a 270mm belt will be included.
If no motor mount is present with in the same order, a 265mm belt will be included.
If you need a specific belt size, you'll want to purchase the wheel pulley, motor pulley, and belt separately.