A sash window consists of two sashes that slide up and down. Often these two sashes will be equal in size, although you do have the option of specifying a custom split. On advanced sash windows such as ours, both the top and bottom sash will come with a slide and tilt facility. For the sashes to slide up without immediately sliding back down, each sash is comprised with a mechanism used to counter-balance the sash eliminating the need for sash weights, sash cords and pulleys found on traditional sash windows. The balances are concealed in the two chambers found on each side of the sash window. Here at Quickslide we use a constant force balance system as well as a spring balance system.