Standard roller covers are 4" long, but can be as large as 18". Roller covers are tubes topped with an absorbent material that slips over the paint roller frame. They are often made of synthetic fabrics (woven or knitted), such as polyester or foam, as well as natural fibers like mohair or lamb's wool. Covers come in a range of nap sizes. The thicker the nap pile, the more paint it holds.

Mini roller covers of 4" or less can be the optimal paint rollers for small surfaces and narrow areas such as edges, corners, trim and frames, as well as hard-to-reach places such as inside bookcases and cabinets.

Metal-tined spiked roller covers feature rows of dense pins that stick out of the cover. They promote self-leveling of coatings and reduce air bubbles. These rollers work well in resurfacing applications with cement-like and gypsum-based materials.