This drive belt is made with a PEN cord and aramid fibre, instead of a standard Nylon cord used in scooter drive belts.
Aramid fibre (often found in body armour) decreases the wear rate of the belt, whilst the PEN cord is designed to reduce elongation and ensure that your belt lasts for longer than a standard drive belt.
When purchasing this belt for the Lexmoto Echo the OEM belt may say 681, however this 669 belt will be the correct size. This is due to the suppliers measuring the belts differently.