If you need a curved stairlift installed the track will be made to order for your staircase. For this reason curved stairlifts are of higher cost than straight stairlifts. Depending on the stairlift users mobility, if they can negotiate the last few steps themslves, then a straight stairlift is doable. A curved stairlift is needed if they can't get to the top of the landing unassisted.