Why do these odd balls follow me home ? Rathbone shows a N15 wrench in Vol III and attributes it to Mast Foos. The problem is they look alike except his picture shows an (S) wrench and my wrench is a straight wrench and it hasn't been straightened.
The other wrench is similar to a Mast-Foos (B5) but is unmarked and may be nickel plated.

Jim. Mast. Foos and Co. Lawn Mower Parts books show two styles of the N15 wrench:



Here's a photo of the marked B5 wrench:

Thanks Bus,
Without a copy of that parts book,I probably would never I D my wrench. Thanks for the pics. I have a couple copies of the marked B5 wrench but hadn't seen the unmarked version if indeed this is indeed the same wrench. Can't find my B5's tonite but will check tomorrow to see if this wrench would be identical.

Whatta you think the little pin was used for? All three seem to have one. CW

 Don't know what the pin was used for.
After looking at B5 the silver wrench is not very similar (like not at all) Silver wrench has hex pin projection;a much 5/8 wide opening and works on something with groove on both sides.
Ignore anvil in photo;its just photo prop.

Jimwrench, I found a wrench marked E15 that looks identical to your N15. It's 5" long, the square open end measures slightly under 9/16" across the flats, the hex open end is 11/16" and the round peg is 23/64" in diameter. If you get a chance would you give me the measurements of your N15?

Bus,
My N15 is 5 inchs long;with 9/16 and 11/16 openings. Peg is roughly 5/16 across casting dia. Looks same as your wrench except marking.