This Smith & Wesson factory part may require Disassembly and Assembly to replace it. Some parts may require installation and fitting by a qualified gunsmith. Factory replacement parts are manufactured to the exact same specifications and tolerances and use the same manufacturing materials as the original parts.
If the grips on your 1911 measure 4" long, you have a Government/Commander length grip. If the grips on your 1911 measure 3-1/2" long, you have an Officer/Defender length grip.