OLN is the measurement of the distance between the outer nuts (that press against the inside of the stays) yeah? If so, that looks to be 126 or maybe 127mm. Difficult to measure more accurately with cassette on, etc. the total length of he axel is almost 1cm longer again - prob 135mm. It's a Hyperglide 7-spd cassette 13-26T) & on the opposite side to the cassette the black washer cap thingy says Shimano FH-HG20.
Hope that helps.
Hope that helps.
