These options provide four inches (4") of additional height from the tabletop upward on standard design desks. Allows extra rolltop clearance (or upper rack bay clearance on high rise version desks) for mixing consoles with larger meter bridges and video monitors (often ordered along with our VIDEOBAY option for extra clearance). Photo shows 2 Extended Rolltops (EXTRT's) with the PLUS4 option on the left desk. PLUS4 applies to low-profile desks, HRPLUS4 applies to High Rise version desks and INPLUS4 applies to the Inspire Series desks (where the sideracks also 'grow' taller to match the desk body). Be sure to always double check your actual equipment measurements for needed clearances.