For cutting a straight edge on a piece of rough lumber or a taper on a table leg for example. I'm not using it since I got a track saw. I can't remember how old it is but it has no issues or meaningful wear and I don't think Rockler has changed the design. They are $100 new, I'd take $60. Pick up on the north side of Bloomington or I can deliver nearby it if you are patient.
From Rockler's website:
With a simple indexed angle setting system, aluminum hold-down clamps and a smooth sliding design, our taper jig makes tapered cuts fast, easy and more precise. Perfect for chair legs, table legs and more, the jig fits snugly in any standard 3/8'' x 3/4'' miter slot and features a large, ergonomic handle for smooth push-action performance throughout the cut. Plus, with the miter bar removed, it doubles as a stable straight-line ripping jig. This jig works with table saws on which the left edge of the right miter slot is 3-3/4'' to 4-3/8'' from the blade or 5'' to 5-5/8'' from the blade.
Features:
Includes 36'' miter bar
Indexing marks make angle setting easy—each mark represents 1° of taper
Dual tape measures provide convenient reference and also help set angles
Two hold-down clamps prevent stock from drifting dangerously from your fence
Clamps have non-marring rubber caps for enhanced grip
Three adhesive strips run across the jig to help stabilize your workpiece
With taper angle zeroed out, jig works great for ripping straight edges on rough lumber