The Cartridge Companion is unique in a sense that you can plug in 2 bullets into the same controller. The thrill of knowing you can have dual pleasure is something that you can be excited about. With its unique design, the controller fits comfortably in your hand and the ease of controlling the 3 speed massager with your thumb is something to be desired. Get an extra bullet and play like you never played before. Can be used in conjunction with SD2034, SD2035 or SD2036.