This is an obscure, but elegant and high-value route up on the upper tier of Rincon, in the same alcove as Bat's Ass Crack, etc. You can either climb a route to get here, or scramble in on the descent ledges leading from the north.
Cuban Bluegrass is on the right (south) side of the alcove, in a right-facing corner with an incipient seam, just around the corner and right Kangaroo (?) Crack. A mossy, easier-looking left-facing corner is just right again, at the very right margin of the alcove.
Boulder up to a fingerlock and place some smallish TCUs. Stretch up and place RPs in the seam, then puzzle through bouldery, sustained, tenuous moves to reach a jug break. 5.10+ climbing up the corner above leads to sling anchors on a tree.
This route could very well merit an S/VS or VS rating -- if the RPs blow -- or if you fall a bit higher than you really should going to the horizontal. While the landing is pretty good, it would still be a 15 to 20-foot grounder.
Small TCU's, a hand-sized piece (1"-2"), RPs, stoppers