The Regular Sand T Perch from Insight by JW can attach to the side, bottom, top of the cage on the outside or on the inside. The natural sand is part of the mold, not sprayed on and helps to keep nails filed smooth while being both comfortable and durable. This perch is also designed with varied widths to resemble a bird's natural habitat and to help prevent sore feet. Suitable for parakeets and cockatiels and other similar sized birds.