My link takes you to nylon washers. I can't see how more than 1mm would be needed. They are a penny each.
You can buy clear bendy ones. I thought that was a good idea, but it wasn't. You can't see if there is one there until you unscrew the razor and the washer drops on the floor.
A lot of razors have a 10mm indent - perfect for the washers to fit in.
M3, M4, M5, M6, M8, M10, M12, M14, M16, M20, Nylon Flat Plastic Washers DIN 125. NYLON WASHERS FORM A FLAT PLASTIC WASHER. washers are the standard form A pattern (most common). Stated sizes (M ) are the bolt size which the washers fit; Hence the hole sizes are slightly larger to allow clearance.
M3, M4, M5, M6, M8, M10, M12, M14, M16, M20, Nylon Flat Plastic Washers DIN 125. NYLON WASHERS FORM A FLAT PLASTIC WASHER. washers are the standard form A pattern (most common). Stated sizes (M ) are the bolt size which the washers fit; Hence the hole sizes are slightly larger to allow clearance.
You can buy NEOPRENE RUBBER WASHERS from ebay for 5 times the price, but it can get obsessional.
Just buy the M5 10x1 black, and the experience will guide you. I've never broken one. I lost one down the toilet and didn't put my hand in for a penny. So don't believe the rumours about my being mean.