These are not as easy to use as other drywall anchors, but they're still good to have on hand for medium (10 pounds to 25 pounds) to heavy loads (25 pounds to 50 pounds). Pointed mollys (right) can be tapped into place with a hammer. Nonpointed versions require an installation hole, and work well in old plaster-and-lath walls.
How to use them: Seat the round flange flush with the wall surface by tapping the screwhead. Turn the screw to "mushroom" the slotted sleeve against the back wall surface. Take care not to overtighten; you'll know this is happening if the anchor flange starts to depress the surface of the plaster or drywall. Once the molly is secure, unscrew the bolt and then replace it with the item in place.
Best for: Towel racks on plaster, heavy-duty shelving on drywall and plaster, curtain rod supports on drywall and plaster, and wall-mounted mirrors (over 20 pounds) on plaster.