1. This slide rule was made by Ricoh. This is a Japanese company which was part of a group of companies who also made and sold slide rules under the Relay brand name. In a sense it would be accurate to refer to the company as Relay/Ricoh.

2. They also made slide rules under several other trade names, usually sold in the U.S. These included Alvin, Charvoz-Roos, Dietzgen, Eagle, Engineers, Jason, Lafayette, Lutz, Micronta, Omega, Pickett (the B1 only), Sans & Streiffe, SIC, Skyline, Staedtler-Mars and Wallace & Wallace. In many cases the companies named did not get all of the rules from Relay/Ricoh.

3. In my collection I have Dietzgen which, on one face but not the other, has an identical scale layout.  It has identical end braces to this Ricoh. However, it is not made of bamboo - used by Japanese rule makers - and it says "Made in U.S.A.". So this was probably not made by Ricoh. I also have a Lutz which specifically says "Made in Japan" (despite being a US government issue rule). This one also has a cursor of exactly the same style as the cursor on this Ricoh rule and is made of bamboo.. One face (though not the same as the Dietzgen) is identical to this rule. The end braces are different. However it was probably made by Ricoh.