A spring buffer is an energy-accumulation buffer fitted in the pit that compresses to absorb the impact of a car or counterweight overtravelling the bottom landing, then returns the energy as it rebounds. Because the stored energy is released again, spring buffers are permitted only for rated speeds up to 1.0 m/s under EN 81-20; above that an oil buffer is required. Spring buffers are simpler, need no fluid maintenance and are common on low-rise residential and goods lifts.