Agency 6 Shovel Knob Wrench Red. The plastic locking knobs eventually failed due to prolonged UV exposure. The Agency 6 Shovel Knob Wrench is the easiest way to deter theft. This billet machined knob is designed to fit over your shovel mount knobs (or limb riser knobs) and let you give them an extra quarter turn. It doesn't seem like much but good luck getting those off by hand. Specifications for Agency 6 Shovel Knob Wrench: Manufacturer: Agency 6 Finish: Anodized Package Contents: Agency 6 Shovel Knob Wrench Agency 6 KnobWrench-RED: Shovel Knob Wrench Red