D-768U…. Sides move independently and are not reciprocating. 31-1/2 inches long closed and opens fully to 96-1/2 inches. 65 inches of space for table leafs. Heavy-duty cold-rolled bonderized steel on 48 tempered steel ball bearings. Both sides open off unitized side piece for rigidity. 1-7/16″ height easily hides behind narrow apron. Mounting surface under top is 7/8″ wide. Each of the 4 separate sections are 1/2″ thick except for the one with the flange which is 1-1/2″ making the total width of slide 3 inches. Note: It is a fact that table slides will sag. By design, table slides must have some play, allowing them to slide. Other factors such as weight, number of table leaves and the amount of added weight placed on table in use, will also affect sag. Shimming slides at the edge where two sides of table meet will help. The best solution is to install folding table legs for added support. H-65800L or S-149L are hinges which can be used for folding legs. Screws not included. Pair of Large Double Acting Slides for Pedestal Tables!