The M stands for micron so you're looking at a 50 micron strainer.

Here's some info from the Wix filter website to give you a point of reference:

"Wix media in the automotive full-flow oil filter is able to trap and hold essentially all the contaminant particles larger than 25 microns. (A human hair measures approximately 70 microns in diameter. An object that is 1 micron in size is .000039 inches in diameter.) Our filters also capture a high percentage of even smaller particles."

Hope that helps

Wrong. 50 mesh means 50 wires per linear inch. Actual micron rating will depend upon wire diameter or gauge used. Normally a 50 mesh is 300 microns.

50 mesh per square inch particile that go through this mesh size will not stop up smallest sprayer tip. I used this filter on boom 12 row sprayer for filtering final filtering before chemical entered 4 spray tips total of 3 filter on unit cleaning out these 3 filters was easyier than clening the 12 small filter at sprayer nozzles.

I used one of these filters inline before a roller pump on the tractor.
I pumped water out of the river that borders our property
and filled up a swimming pool. Took 3 hours to pump it full.
The water looked clear in the river, but is green in the pool.

Thanks for the info.

Pooh Bear