Hello
Can you advise what size the o-rings are for a Stihl RE117 pressure washer - item 21 on the diagram, not listed but I'm sure that once I know the measurement you'll not doubt have it or listed elsewhere? I've taken one off and it measures 15x10x2mm but cannot see that under the parts.
I have had a look on the Stihl diagram for you and part no. 21 only comes as either part of the valve which is this one:
https://www.lsengineers.co.uk/valve-for-stihl-re142-re162-part-no-4738-700-6200.html
or as part of the set of seals:
https://...
