E. Emerson End Stop for Straight Edge Clamping Tool Guide, upgrade part XCSB. For Contractor Series with recessed tracks.Check out Wide Jaws: http://www.thingiverse.com/thing:379387This is an end stop for Contractor Series E. Emerson Straight Edge Clamping Tool Guide. The part is reversible by only switching the adjustable end. The adjustable piece is a 5/16" Hex Bolt with 2 matching nuts (minimum length being 1"). One must be hot pressed into the space on the end stop itself. The other nut is placed on the bolt to tighten the position so that the end stop can be perfectly set to desired measurement. *You may not want to put an extra nut on the other side if you prefer using a longer 5/16" adjustable bolt. The 2 (#8 - 32 x 1.25") machine screws the fit through the knobs upside down to lock the end stop in the recessed tracking. The nut for each of these is also hot pressed into the end stop knobs in order to create a tight fit and a solid clamping mechanism to hold the end stop in place. (Look at picture for configuration) There are small guides that match up with the ruler on the Clamping Guide, although not sure how useful. Parts: 5/16" x 1" Hex Head Bolt (x1) 5/16" Nut (x3) 8 - 32 Machine Screw (x2) 8 - 32 Nut (x2) Suggest higher infill so that piece last longer. Fitting is really tight and can be threaded or heated for better results.