I bought this to substitute for a Coopers AZF011, which is a declared equivalent. It is to fit in a Purolator housing. The hole in the middle at both ends was about 1/4 mm smaller than the seatings in the housing. Since filing would be inadvisable, I was fortunate enough to find a tube expander that fits (we are a railway and also have steam locos). Be aware that it also needs sealing discs to its ends, which are not included, although the housing to head seal was the correct narrow pattern and fitted well.