Portable reference laser unit and attachment accessory

A laser unit for providing at least one of a laser level line and a laser plumb line, where the unit includes both a locked mode and an unlocked (or auto-leveling) mode. In the unlocked mode, the laser unit is configured to provide at least one of a level line or a plumb line when the pendulum assembly is free to settle to a point of equilibrium. In the locked mode, a pendulum locking mechanism locks the laser assembly into a fixed position regardless of the orientation of the laser unit. Optionally, an attachment accessory may also be provided. The attachment accessory preferably includes a ball and socket joint attachment assembly that is configured for attaching the laser unit to the attachment accessory such that the laser unit can be rotated or tilted with respect to the attachment accessory.