Anodized aluminum footswitch nuts. Available in a variety of colours. Sold individually.
These are great for colour coding your pedals or just making them look cool.
Tech's notes: "These fit on every type of SPDT, DPDT, 3PDT, and 4PDT footswitch we currently offer. They do NOT fit the smaller SPST footswitches, mini switches, or 1/4" jacks."