Our garage door opener 4L370 V-belt from North Shore Commercial Door will replace most brands of V-belts that are exactly 37 in. long and 1/2 in. wide. Rubber V-belts wear out over time, requiring a quick replacement before any dangerous breaks. Replace yours at the first sign of wear. Our 4L370 garage door opener V-belt is 37 in. long and 1/2 in. wide. It's a durable rubber belt engineered to resist damage from heat, oil and corrosion.