Martin offers two complete lines of jaw couplings, one for greater horsepower and one for interchangeability. Features include no lubrication, easy installation, no metal to metal contact resistant to oil, dirt, sand, moisture, grease, easy inspection of load carrying spider, flexibility of angular or parallel misalignment of shafts by Buna-N spider member permits smooth power transmission. Buna rubber, Hytrel® and Urethane spiders are stocked in all branches. Martin Jaw Coupling Hub, Bored-to-Size, Series: ML Universal, 190 Coupling, 1 in Bore Dia, 4-1/2 in Hub Dia, 3600 RPM Maximum, 1.938 in Length Through Bore, Steel