ZB Custom was a brand of steel guitars designed by Zane Beck and built by him, Tom Brumley and some others.
They sold one fuzz pedal that looks like a Mosrite Fuzzrite, which were made after Mosrite went under in 1969. Not much is known about this pedal, even Ed Sanner, the designer of the Fuzzrite, doesn't know about it. There are 2 links between Mosrite and ZB:
After Mosrite went bankrupt they used the old Mosrite building at 1424 P Street in Bakersfield, California, before moving to Arizona, possibly they used old Mosrite parts to build some pedals?
John Rutledge worked for Mosrite of California until they went bankrupt in February of 1969:
I think it was March the 1st (maybe a day or so one way or the other) that I went to work for the ZB Guitar Company. Zane himself taught me how to build the complete guitar, we even made the cases for them. The company had moved to California in 1968, I don't know exactly which month. The owners of the company moved me and the company to Phoenix, Arizona on February 1st 1971. I was at this time General Manager of the company. In January of 1972 I came back to Bakersfield, and went to work for Mosrite of California. After I left ZB, Bill Sims, the owner of ZB Custom, had Zane Beck come to Arizona to help him run the company, and find someone who was qualified to work and run the company.
So maybe Mosrite made some pedals for ZB after that?