OFFER: Stand-off washers (Innsworth GL3)
DESCRIPTION
These are made of hard nylon I think . They are 1 inch diameter by varying thicknesses with a 5/16 inch hole though the middle.
This might well be them: https://hawkeng.co.uk/index.php?route=product/category&path=70_128
They are stand-off washers and are used for aligning go-kart seats, car seat sliders and various other DIY uses.