These clock repair kits are specific to the clock that you are working on. These items are the common items for the repair of the clock listed. There is a section for repairing cuckoo clocks, another for 400 day anniversary clocks, and then there is spring driven or weight driven. To say a clock is spring driven, means that there are mainsprings contained within the movement itself that powers the gear train to run usually 8 days on a full wind. Weight driven clocks run the same amount of time but the clock is powered by gravity powered weights rather than springs.