Aluminum plate 1/4 inch thick To go under the deck to secure the mount base to the deck.

Sandwich the deck floor between the mount base and the under plate. 

Three 5/16 stainless steel bolts 2 inches long. With 5/16 stainless steel nylock nuts included.

Fits mount base  Doe's not fit Telescoping base. 

Under Plate For Monitor Mounts