The Treetop Friends Musical Mobile will put your baby to sleep playing the classic Brahms' Lullaby. It has luxurious linen branches and whimsical Treetop characters that bring a soothing nature scene to the crib. Music box has on/off switch. Plastic clamp fits standard cribs with top rails up to 2 3/4 inches tall or less. Non-standard crib rails may be taller than 2 3/4 inches and may not work with this mobile frame. Mobile will not affix to solid wood sides such as a sleigh crib.