Martin 80-70 Sprocket & Gear Chain 70 Teeth Weighs 75-Pounds Note Dimension - we have 1 of these Martin Sprocket & Gear's with 70-teeth and weighs 75-pounds available. No sure what this chain gear fits or weather its used for a chain gear at all. The original OEM packaging didn't have any part numbers and the chain gear did have the OEM Martin 80 * 70 numbers.