Bolted onto the underside of the tail end of a skateboard, the tail guard (also known as a "skid plate") protected the tail end from skid stops and other maneuvers that would otherwise wear away the wood (commonly known as razor tail) and decrease the longevity of the tail. Typically made of plastic, these were widely popular in the '80s but their usage quickly diminished with the arrival of two-tail board designs, which became increasingly popular in the '90s.
Decks come in a variety of shapes and sizes. You can choose a mini-board, a cruiser, a drop-through or a standard deck for your favorite set of wheels and hardware. Widths range too from a few inches with a 22-inch board to the wide size of a true cruiser. Some decks are flat as possible while others are significantly concave for optimized turning. You can buy a deck with artwork and grip tape already attached for a quick install or you can get a bare-bones wooden deck to truly customize.
In 1982, while competing in the Rusty Harris contest in Whittier, California, Rodney Mullen debuted an ollie on flat ground, which he had adapted from Gelfand's vertical version by combining the motions of some of his existing tricks. Mullen used a "see-saw" motion, striking the tail of the board on the ground to lift the nose, and using the front foot to level the board in mid-air. While Mullen was not initially impressed with his flat ground ollie, and did not formally name it, he realized it opened up a second, elevated plane on which to perform tricks.