Spectra Precision DM-20 Dozer Bolt-On Mast The Spectra Precision DM-20 Dozer Bolt-On Mast is a rugged machine control mounting accessory designed for secure installation of compatible LR series laser receivers on dozers and grading equipment. Its adjustable bolt-on design installs without welding and mounts directly to machines equipped with common factory mounting configurations for fast setup in the field. Key Features • Compatible with all Spectra Precision LR receivers • Adjustable bolt-on mast design requires no welding • Mounts to popular factory machine configurations • Ideal for dozer and grading machine applications