The Loos professional tension gauges measure the tension in cables and rods from 3/32 to 3/8 inch in diameter (2.5 mm to 10 mm). These gauges are designed for setting the proper tension in the standing rigging of sailboats and also for other applications such as supporting cables for radio towers, large tents and other structures. The gauges are relatively inexpensive and are designed to be suitable for rugged marine service. The "Professional Models" provide an increasing durability, accuracy  and convenience of use. The gauge may be hooked on the wire and will remain in position while the tension is adjusted. Manufactured of rugged anodized aluminum, this gauge is corrosive resistant and will give years of service. Detailed operating instructions are included with each tension gauge. Professional Models - Higher accuracy and easier to use than standard models. The cable can be adjusted while the gauge remains on the cable. "Just watch the pointer move." All readings are based on 302/304 1x19 S.S breaking strengths. The gauges measure tension over a range of approximately 5% to 25% of the breaking strength of the cable and provide an accuracy of + or - 5%. GAUGE SIZES: PT-1M : Cable size 2.5mm, 3mm, 4mm PT-2M: Cable size 5mm, 6mm, 7mm