SP pulley with closed ball bearing
This range of pulleys has the following features:
Highly quality polyamide pulley
Precise shielded bearing with small tolerances, lubricated, grime resistant
SP pulleys are recommended for more precise applications because of their high rotational speed and high bearing load
for different cable dia, other pulleys are necessary, see:
https://www.carlstahl-technocables.com/products/pulleys/sp-pulley-with-closed-ball-bearing.html