Check the listing for details. SL728 #7 .177 Wire 28" Lock End Extension Springs for One Panel Garage Doors. Condition: New. Listed at 79.95 USD. SL728 #7 .177 Wire 28" Lock End Extension Springs for One Panel Garage Doors Determine your garage spring size Examine the label at the end/s of your existing springsFIRST LETTER/S: these determine the securing mechanism or type of spring. A lock end springs label will start with SLFIRST NUMBER: this is the gauge of wire that the coil is crafted from. A 7 means 7-gauge wireSECOND NUMBERS: these determine the physical length of the spring 2. If your spring is missing its label Get a tape measure or rulerPlace sideways over the coil to get the diameterPlace it lengthwise and measure the length of ten coils, then divide this number by ten. This will give you the wires size/gaugeSpecifications Curved, locking pins secures spring at both endsRated for 9000 cycles of operationWhen adding to cart, please select a spring size:SL728 - 28 IN Lock-End Spring (.177 IN #7 Wire)SL730 - 30 IN Lock-End Spring (.177 IN #7 Wire)SL732 - 32 IN Lock-End Spring (.177 IN #7 Wire)SLR729C - 29 IN Lock-End Spring (.177 IN 7-Gauge Wire) Designed for use with the E900-R Tension-Lift Hardware Kit for Single-Panel Garage Doors Replacing hook/joining hardware to match tension of a new spring is strongly recommended Single-spring assemblies will use a C-Hook Double-spring assemblies will use a W-Hook