It's 11.3mm. Considering how long I've used it, the condition is pretty good, but there are some scratches and areas where the plating has dulled. The arm is not made by Callaham. I've forgotten where it's from, but it doesn't have much play. I didn't notice anything unusual when using it normally. The screws are also not Callaham. I've forgotten the manufacturer. The Raw springs in the image are not included. I'm open to some price negotiation, so please comment if you're interested. #Stratocaster #fender #bridge