toothed portion 84 that extends inwardly into the slide rail 31 from the downwardly extending portion 82 in the preferred embodiment the body 85 the downwardly extending portion 82 and the toothed portion 84 are made of a single piece of material in the preferred embodiment the material is stainless steel but any suitably strong and durable material can be used the toothed portion 84 has at least one and in the preferred embodiment two teeth 84 the teeth 84 pass through a slot 57 in the downwardly extending wall 52 of the upper slide 50 the teeth 84 are sized to engage the apertures 48 in the upwardly extending wall 42 of the fixed lower track 40 when the user moves the latch handle 81 away from the left slide 31 the teeth 84 are removed from the apertures 48 which allows the upper slide 50 to move when the user moves the latch handle 81 back toward the left slide the teeth 84 engage the apertures 48 and lock the upper slide 50 into place the coil spring 87 forces the latch 80 around the pin 73 and holds the teeth 84 into place in the apertures 48 such that the slide assembly 31 cannot move this prevents the slide assembly 30 from adjusting its position it is important that the teeth 84 be sized to snuggly fit into the apertures 48 to prevent inadvertent movement of the slide assembly 30 in the preferred embodiment the apertures 48 are approximately one quarter of an inch wide and are spaced apart approximately one quarter of an inch this means.