The gaiter adaptor is used to seal the outside of a 1/2" diameter barrel against the hazardous environment in which the tong head assembly is being used. The adaptor is for use with a standard gaiter and this is attached via the plate and screws as shown.

The section to the left shows how the adaptor and gaiter interact to seal the barrel.
The gaiter is clamped to the adaptor, and an internal seal is forced against the outside of the barrel through the clamping force of the screws, and the shape of the internal sleeve.

Potentially a leak path for gasses still exists inside the barrel rendering this type of assembly for use only in non-toxic environments. For toxic environments the Bayonet type barrel is recommended.

It must also be noted that gaiter change cannot be completed without destroying cell integrity.