SeaLux Universal Heavy Duty 360 degree 7" to 8-3/4" Seat Swivel Base Mount Plate for Bar Stool, Chair, boat or van pilot seat (Large) This is a replacement flat swivel zero tilt that goes between the seat and the frame of bar stools. SeaLux Universal Heavy Duty Seat Base Swivel Mount Overall Dimensions: Plate 7"x 7"; Diagonally Measurement: Plate Corner to Corner: 9-5/8"; Hole Far Reach: 8-3/4" ;Hole Center to Center: 8"; Hole Near Reach: 7" Maximum Capacity: 500 lbs.. Mounting Adjustable from 7" to 8-3/4" Perfect for passenger seating and front bow fishing seats on marine boat. the 52 ball bearings inside allow for 360 degrees of movement. opening slotted holes for univeral fit, mounting directly to most standard seats and pedestalsthe Black EDC (Electrostatic Discharge Coating) finish for corrosion resistance.