An alignment device (10) for indicating alignment between two component parts, the first component part (12) having an arcuate track (14) with a track following member in the form of a ball bearing (28) to follow the track under the influence of gravity to seek an equilibrium position. The body having a signal input (18) and a signal output port (20) and the second component part comprising an alignment member axially mounted within the body in restraining engagement with the track following member (28) so as to be rotationally displaceable within the body in response to displacement of the member 28, whereby alignment between the alignment member and the input and output ports in response to displacement of the alignment member by the ball bearing, effects operation of an indicator means to provide an indication that such alignment between the alignment member and the alignment ports has been achieved. Further, there is provided a level indicator utilising such an alignment device, together with a power tool utilising such a level indicator to determine when such a tool is held in a horizontal or vertical plane.