The colorful plastic holder attaches easily to the cage by hooking onto the bars of the cage. To keep it even more secure, can also hang it from the JW Pet Treat Stick Holder, which features a curved perch and bottom tray to cut down on spills. Can be used with any type of millet and also be used to hold similar pet bird grasses and other stemmed treats. Great for parakeets, canaries, cockatiels and finches. Easy to remove and clean.