It is made by Gold Eagle Co. in Chicago, IL. It is not cheap. About $37 retail for a 32 oz bottle, which will do a 40' roof.
It "used" to be the only product that DICOR recommended for their roofs. Now they have their own DICOR product (I really think it is 303 in their packaging).
I managed an RV Parts and Repair store in Yuma, AZ for about 10 years, and sold just about every rubber roof product made, but found none that surpassed 303. Our recommendation was to use a 409 or simple green solution to clean the roof with a stiff brush, and then apply 303.
When you apply 303, it will dry to a hazy film. You then go back and buff that film, and you will get a semi gloss finish. When you first start applying the product, you will think that you'll run out, but once the cloth gets saturated, the consumption is a lot less. We normally used some type of terry cloth applicator (old wash cloths work well). Buff with an old towel. The terry cloth helps work the product down into the EPDM roof, which normally is not a smooth finish.
Amazon has a good price. $18.46 for 32 oz, and 41.65 for a gallon.
Hope this fills in some of the blanks.