The pieces of wood slide until reaching the maximum extension of 700 mm and the minimum of 550 mm, due to the two metal plates that make all the pieces in one. To fix the longboard to the desired extension, there are two clips next to the outer arms of the longboard. When released, they allow an easy slide of the piece, but when closed, they press the wooden arms against each other, fixing them.a much easier task when it can not be used.