The Thermacell R-4 refill pack is a 48 hour refill pack consisting of 4 butane gas cartridges and 12 active ingredient platelets. All Thermacell units use the same refill products. One gas cartridge lasts up to 12 hours, one active ingredient platelet up to 4 hours. Gas cartridges and active ingredient platelets can be stored and do not have to be used up immediately. Unused active ingredient platelets are packed airtight to maximize shelf life.