Shimano brakes.

[Ramshawlad]

In an advert for a Shimano 600 tear brake calliper the dimensions 39-49 mm are included. To what do these dimensions refer to?

 

[Webbo2]

In an advert for a Shimano 600 tear brake calliper the dimensions 39-49 mm are included. To what do these dimensions refer to?

I think it refers to how low and how high the brake blocks go.

 

[roubaixtuesday]

In an advert for a Shimano 600 tear brake calliper the dimensions 39-49 mm are included. To what do these dimensions refer to?

"Reach" - Article here describes

https://www.sheldonbrown.com/calipers.html