Check the listing for details. Lumberjack Tools Log Lock Heavy Duty Bundle LL1545HD & LL2580HD. Condition: New. Listed at 287.10 USD. Secure your logs in place while cutting tenons, tapering the log, peeling the bark and more with our Log Lock™ Heavy Duty Bundle, including TWO Heavy Duty Log Locks™. These heavy-duty Log Locks™ are designed for high production users. The Log Lock™ Heavy Duty - LL1545HD can accept logs 1-1/2" to 4-1/2" in diameter. The Log Lock™ XL Heavy Duty - LL2580HD can accept logs 2-1/2" to 8" in diameter. Heavy Duty Features:The threading is cut coarser on the handle nut, jam nut & carriage boltSTANDARD hardware uses ½" – 13 UNF (Unified fine thread). UNF is commonly used in machine screw partsHEAVY DUTY hardware uses ½” – 10 ACMEUNF threading is shaped like ^ whereas ACME threading is shaped like a trapezoid. It will take a much greater force to strip this kind of threadingThe standard 13 UNF is good and works for 80% of customers. The 10 ACME is designed for high production users