Cutting rigid and semi-rigid material

A knife comprising a blade (118), a handle (102) surrounding at least a portion of the blade and comprising a blade opening (135), a blade shuttle (116) carrying the blade shuttle blade is 5 longitudinally displaceable relative to the handle (102) from a rest position to a first extended position and the rest position to a second extended position, different from the first extended position, blade protruding a first distance through the blade opening (135) in the first extended position, and a second distance through the blade opening (135) in the second extended position, a trigger (104) associated with the handle and adapted to be moved to at least one actuated position to drive the blade shuttle from the rest position to the first extended position and the rest position to the second extended position via a transmission (109) interposed between the trigger and the blade, characterized in that the blade shuttle (116) is coupled with the handle such that, when the blade engages a workpiece, the blade shuttle moves from any one of said first extended positions and the second to a cutting position and when the blade disengages subsequently the workpiece, the blade shuttle is automatically retracted from the cutting position to the rest position, regardless of the trigger (104) of the knife is in an actuated position or not drive.