We have been selling these spring wound mechanical appliance type twist timers for many years. They are simple but work great. If you have a piece of equipment that no longer works because the digital timer has quit- then we may have your answer.These work well on battery chargers- ultra sonic cleaners- centrifuges and other pieces of equipment. Timers by diehl poltik include the t-85-600 & 601 timers. Twist timers or spring wound timers can be used to replace expensive digital timers and save money. We have 6 min 15 min 20 min 30 min 60 min and 120 min duration's available.These timers are used mainly for equipment but some models are used for tanning bed timers as well.