From the reviews-
"Was concerned about the size as it wasn't listed anywhere, but they fit great on my 7/8" bars (bar ends I ordered were 7/8" and fit well)."
They will fit the 636.
A few cruisers have 1 inch diameter grips for a fatter look, and most other motorcycles use 7/8 inch diameter grips.
"We have created a Star Wars civilization, with Stone Age emotions, medieval institutions, and godlike technology. We thrash about. We are terribly confused by the mere fact of our existence, and a danger to ourselves and to the rest of life.”
― from Edward O. Wilson, The Social Conquest of Earth.