Maxell brought out their UDXL High Output / Extended Range tape with back-coating in the late 1970s. This is a type 4 tape (+3) according to our nomenclature that required a higher bias.
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse
Maxell UDXL / XL1 High Output Extended Range Tape - Reel to Reel Warehouse