A modular golf club head with an improved adjustable weighting system for an iron and/or wedge type golf club head is disclosed herein. In accordance with the presently disclosed technology, the golf club head may include a body. The body may include a striking face and a back. The back may include a recessed channel. The golf club head may include a weight assembly. The weight assembly may include a movable weight installable within the recessed channel and movable therein, a slidable cover to engage at least part of the recessed channel, and a fastener. The movable weight may include a compressible polymeric material.