Precisely aligns individual steel stamps to help ensure characters are straight and evenly spaced when stamping caliber designations on barrels. Allen head screws allow adjustment for accurate character spacing, so you get truly professional looking results. Machined port allows an unobstructed view of the first stamp head to ensure correct positioning on workpiece prior to tapping with your hammer. Accepts ¼" square stamps with 1/16", 3/32", or 1/8" character sizes. Fits barrels up to 1-3/8" diameter. SPECS: Aluminum, natural finish with steel U-bolt and hardware. 2-3/8" (6cm) long x 3 1/4” (8.2cm) wide, 1 1/2” (3.8cm) high.