When the SNES was released in America replete with redesigned casing, instead of using a different lockout chip, NoA changed the shape of the cartridges, putting two small plastic tags inside the cartridge slot to prevent Japanese cartridges being inserted. Enterprising importers, realising that this was the only thing stopping Japanese carts running on US SNESs began making what they called universal adapters (everyone else called them bridge adapters). These were PCBs encased in plastic with an edge connector at one end and a slot at the other, and a straight bus running between them. The universal part came about because the board was just long enough to poke out the top of the cartridge slot on a Super Famicom, allowing US games to be played. I've heard them reported as wobbly and unreliable (this is probably where "adapter damage" comes from), and they are useless to anyone with a UK SNES without a lockout bypass.

If you have a US SNES, a far better way of playing SFC games is simply to break the tags off with a good set of pliars. Strangely enough, I've seen a Japanese SNES game that has been placed in a remoulded cartridge with slots where the tags would fit. Some US gamers have taken to the habit of filing these slots into the cartridges themselves.

A good bridge adaptor (one shaped like a SNES cartridge) is still of use to someone with a Super Famicom or UK SNES with lockout bypass, because it wouldn't look too pleasant to file the sides of the cartridge port down to allow US games to fit.

UK Mega Drive and Genesis owners used a similar device for playing Japanese Mega Drive games, until Sega, Konami, et al cottoned on to this, and started checking the frequency of the console before allowing the games to boot. Though until this happened, those adaptors generally were "universal".