Seat slide with 5" of fore and aft travel. Swivels 360 degrees with adjustable locking knob. 4 bolt pattern that fits virtually all seat brands. It's 15" fixed height but cut be easily cut down to the perfect height for your boat/seat. 9" diameter base plate with recessed mounting holes. 2 7/8 diameter post. They are all aluminum. They are brand new. They are just over $500 new to buy. $395 for both.