Crain 188 Hinge Scriber is a sheet vinyl seam scriber designed for accuracy, ease of adjustment, and for good grip and control. The offset distance between the bottom guide and the needle is adjusted using a precision thumb wheel. Once adjusted, the three arm knob locks the needle in position. The hinged base allows the tool to be more easily inserted at the seam, particularly on thick material. With the hinge folded open, insert the base under the material on top and hook the guide on the edge of the material underneath. Fold the hinge back and the needle is positioned on the top piece of material and ready to scribe. Crain 188 Hinge Scriber needle height is adjustable for different thicknesses of vinyl. Range of offset adjustment: 11/32". Replacement needles: No. 129.