Maple table extension slides for use building custom tables with adding a leaf. There are two slides sold in this set. The closed dimension is 28 inches fully extended is 54 inches which leaves you a maximum opening of 26 inches these work great and are super heavy duty. These will last as long as the custom custom table your building does.

Here is the details from tickler

https://www.rockler.com/extension-slides-36-length

Operates smoothly, prevents sagging or binding and allows a wide range of leaf openings. 36'' slides are ideal for large rectangular tables. Gives maximum opening of 38 or 64''. Generally the length of the closed slides should be at least 2/3rds the length of the closed table. Sold in pairs. Available in wood or steel.