Ceiling hooks are best for use in wood so they are especially suitable for hanging chair hammocks indoors from the ceiling*. They can also be used in 'partition' walls (where there is a wooden frame supporting the wall). They are also suitable for use in concrete or masonry but then they require a 16mm drill bit.
Each pack contains one screw, fixing instructions and an optional raw plug (for use in masonry or concrete).
*nb. When hanging a chair hammock using a ceiling hook, always use a small piece of rope between the hammock and the chair to allow the chair to rotate freely without unscrewing the ceiling hook.
Please check your hammock fittings regularly as the motion of the hammock can cause loosening of the screws over time.