This is a Ergo Grip Grip Panel known as the XTRO, model 4520-BK.
ERGO's XTRO Officer's Model Tapered Bottom Hard Rubber 1911 Grip is a heavily textured" minimally abrasive grip for Officer Model 1911 frames. Its thin profile attaches with standard grip screws and is designed to accommodate ambidextrous safety options.
Features:
Fits Officers Model 1911 frames
Thin profile attaches with standard grip screws
Designed to accommodate ambidextrous safety options