8" vinyl scriber works both as a wall scriber and a seam scriber. The tool has a rounded end guide for wall scribing, and a bottom guide for seam scribing that runs along the edge of the bottom piece of material as the top piece is being scribed. In addition, the red housing has a hole in its bottom for a second needle which allows the tool to scribe circles or feature strips. The 8" bar allows approximately 6" of length adjustment using the large steel thumbscrew. Needle height is adjustable for various material thicknesses using a screw in the front of the bar.