Surface ground and hardened tool steel bars in ten thicknesses - Recommended by agency armorers and top pistolsmiths as the most accurate way to remove vertical slide “play” from the 1911 Auto, its variations and copies. May be slower than the quick-and-dirty methods, but gives an infinitely more accurate and professional job. Basic procedure as follows: Measure gun’s slide rail thickness; place closest-sized Slide Fitting Bar in frame “way”; tap frame rail with light hammer to close the “ways” space down to match the slide rail thickness. Complete instructions included.