Spirit Bubble Level Accurate Standard Levels ,Acrylic Screw on Level, 55mm Long, Sensitivity 34&prime;/2mm , 4 Pics High quality, high optical clarity plastic CNC machined bore.Sensitivity 34'/2mm bubble movement Black lines, internally printed gives minimal parallax error Yellow/Green Filling liquid Applications:Instrument levelling.Hand held tools requiring a screw on level . 4 pics