The Uno Cartridge is designed for high precision dispensing(1 treat) and to use soft or slightly larger treats. To achieve these benefits the capacity is limited to 15 treats per load. Having more than one allows you to quickly and easily swap cartridges without having to refill treats. Have a cartridge in your car, your purse, or anywhere you might want to train!
Treats that work in the UNO : Zukes, Happy Howies, etc.