Made of a durable plastic. It's got a brass insert and a flat head set screw.
Measures 20 x 11mm
Shaft opening- 1/4" or 6.4mm
Beginner's Tip: The term "MXR" refers to the aesthetic design of the knob, popularized by the pedal manufacturer by MXR. Just because this is an MXR-style knob does not mean it automatically fits on all MXR pedals. The right fit depends on the shaft size of the knob's potentiometer. Read this post to figure out what kind of knob you need: https://lovemyswitches.com/news/what-knob-will-fit-on-my-gear/