Honda HRS21 Owner's Manual page 24

Discharge Adaptor
The adaptor is subject to wear undei normal usage; check frequently for
damage, and make sure the nuts and bolts are tightened. Replace, if
damaged, with a Honda genuine adaptor.
When the adaptor 'needs cleaning, wash it with water and dry it thoroughly
before using.
6 mm bolt
(PVA and SVA types)
22