Adapters are fittings which connect two connection fittings with one another or which seal a connection against the environment. In detail, one differentiates between:
- Twin nipple - with the same male thread on both sides
- Reducing nipple - with different male threads,
- Reduction coupling - with female thread on one end and a male thread on the other end
- Muffs - With the same female thread on each end
- Reduction sleeves - with unequal female threads
- Weld nipple - with a weld end on one end and a male thread on the other end
- Screw flange nipple - with a fixed flange on one end and a male thread on the other end
- Filler plugs - a closure with male threads
- Protective caps - a closure with female threads
