Revolutionary design to groove a 1/8 "thick shackle base with toe or tipped. Can groove a shackle base with heights between 4" -6-1 / 4 ". Can also groove a base 2-1 / 2 "high shackle with over adjustment and attachments. With the included nylon pad, it can also groove a 4 "mmx 080" base. 2 tungsten steel blades form a 102 ° "V", which covers 99% of the inside angles. Easy to install and very quick to make perfect grooves.The grooving depth, grooving length and clamp tightness are all adjustable.