Tandemkross Ruger Mark IV 22/45 (factory or Cthulhu Lower) Accelerator Forward Thumb Ledge, Black (Red Additional $5) (opens in new tab)

TANDEMKROSSs new Accelerator Forward Thumb Ledge helps improve grip and control. With the scalloped texture, you get the support you need for steady, rapid, and accurate shots. Encourages proper grip.