These fixings are specialised for fixing a large, heavy item to a dry wall. The fixings work by drilling a large hole with a holesaw and then pushing the fixing into it, the fixing will spring open in the cavity and give you a strong support for your item. The fixings come in 5 different sizes each with a different maximum load.  

A cavity fixing that is ideal for overhead installations. The wings spread the load over a wider area making them more suited for heavier loads.