ROBERTS Pro Dual-Depth Carpet Knife is a must have for carpet installers. Expertly designed, this knife provides tool-free, easily adjustable blade depth options: 9/16” or 13/16” to accommodate different carpet-back thickness. Ideal for use with round- or square-end slotted blades, the Pro Dual-Depth Knife features SWIVEL GRIP, a patent-pending blade spindle that stores most brands of 10-packs cartridges and up to 20 single blades. The molded comfort grip and ergonomic design increase leverage and pulling power. The magnet on blade holder holds blades in position while open; Knife cavity fully butterflies for full access and easy blade change.