The Osborne miter guide sliding stop flips up out of the way when not in use. Fence has abrasive surface to absolutely prevent movement during the cut. No clamp needed. Heavy-duty steel T-slot washer (removable). Fence extension carries the flip stop and adds support up to 42" from the blade. Index graduations are clean, crisp and easy to read. The scale is large enough to set half or quarters of a degree with confidence. A simple locking calibration mechanism is provided if you need to make adjustments. Patented extension arm assembly makes it possible to quickly and easily find any angle and lock it securely in place. Precision detent plunger auto-locates common angles. The guide bar actually expands in 3 places to provide the perfect fit for most saws with standard 3/4" x 3/8" miter slot. The fence can be adjusted from side to side allowing tight clearance at the blade. Quickly reverse the guide for left or right hand use by removing the fence, reversing the extension arm and reconnecting the fence. So simple... So stable! The greatest innovation in miter guide design in over 100 years! DONT WASTE TIME WITH A PROTRACTOR GUIDE ANYMORE! The patented triangular design makes this guide more rigid than any other guide. Such a simple design. So easy to set precise angles.