The 21577E Naomi BIOS, burned and tested onto an EPROM and ready for you to install.
The 21577E EPROM is a popular BIOS in the US, as all games that support it have English text and game titles (Virtua Tennis, as opposed to Power Smash, for example), but it plays US capable software. Most software has US compatibility, the most notable title lacking it and requiring a JPN Bios being Street Fighters Zero Three Upper. However, some games, like Ikaruga, play fine and display Japanese text under this ROM as well. The 21577 indicates USA region, the "E" indicates revision E, with full compatibility with DIMMs, NET DIMMs of any software revision, GD-Roms, and link hardware.
Attention - this does not get SHIPPING calculated correctly if ordered alone - if ordering alone, I can give you a lower/custom shipping quote for USPS flat rate small box. Please email us for orders of this type.