GS-VLG-1 Visu-Lok Grip Scale from Omega Technologies is suitable for Visu-Lok®, Jo-Bolt, Huck Blind Bolt and Tension Lockbolts. Markings are electro-etched for durability. A 3.8mm (.15”) tip easily fits into 4mm or 5/32” holes. This grip scale may be used for selecting flush or protruding head fasteners. Graduations are in 1/16” increments.