THUMB.TAC Trim Reveal Tool – 1/4″ & 3/4″ Offset – Finish Carpentry Tool for Door & Window Jambs – Solid Nylon – Precise Marking Gauge – Made in USA. Ideal for cg, sills, and finish carpentry work. ERGONOMIC THUMB POCKET DESIGN: Unique thumb style grip provides a secure, tactile feel against the jamb, ensuring consistent reveals and confident one handed use on the jobsite.