E. 20th Street at 22nd Avenue
This is a real definitive example of a Schnoor Bros. mark from 1915, which I believe is the firm’s first year. P. Schnoor & Son used the same mark, and I have examples from 1911, 1912 and 1913.
Notice that all the 1’s are backwards, and the dash in the date is also a backwards “1.”

7 May 2023 at 12:26 pm
Found one of these in Berkeley this morning. I wasn’t paying super close attention to the location but I believe it was on Derby somewhere near Acton. That one is marked 4 – 1915, also with backwards “1s” and a backwards “1” dash. The “5” looks a bit odd too, as if it was altered from something else or perhaps just added by hand.