Grow-U-Groove Pulley Roller Guide Wheel 8x40x20.7mm 4pcs 0840UU U Type

Made of high quality material, these pulleys are durable, sturdy and portable.^
Internal lubrication grease, smooth operation, good mute effect.^
U-shaped groove design, smooth surface reduces friction.^
There are total 4 pulleys in one set which you often use for many projects.^
Widely used in doors and for tracking and driving mechanical equipment.^