Material: Polyacetal resin in die-cast version, colour black.
Bores machined. High hardness and low coefficient of friction which
means they can be used in various set-ups, e.g. also under water.

Note regarding pulleys made of polyacetal resin: Inside these
die-cast parts are some cavities caused by production. These parts
should therefore not be drilled too deep. With larger bores or when
grooving the cavities might become visible. This often does not affect
the functionality.