An anti-grav sled is a device used to carry objects which are too heavy to lift manually. The technology used is similar to a hovercraft or anti-grav lift.
Kasidy Yates and her crew sometimes used anti-grav sleds to transport cargo into her cargo ship. Although Sisko suggested using the transporter instead, hers was a Mk. V, which was ill-equipped to transport unstable bio-matter. (DS9: "Family Business").