This is a Pachmayr Base Pad known as the Grip Extender, model 03889.
Pachmayr's new Grip Extenders will greatly increase your control and shooting comfort when added to popular compact and sub-compact handguns. The extensions perfectly match the shape and texture of the handgun" so they look like they are part of the pistol" rather than an add-on. Extenders are easy to install and are made of tough" high strength polymer that stands up to the roughest handling.
Features:
Easy to install
Design matches pattern of the host pistol