White nylon plastic with a matte finish and slight grainy feel.
About this Product
Bugaboo Locking Disk Right Side (Non Brake Lever Side) This model is solid for maximum strength when used with plastics. It costs $50 in stainless steel so I had a hollowed out version made for the stainless steel option.
There is a good video by a Norwegian repairer I've added a link to. Only two things to add I use a painters knife to hammer under the dome first to protect the plastic from the bigger screwdriver and I use silicone spray not WD40 to lubricate as it is a dry lubricant and will not attract dirt.