It's supposed to be standard size- unfortunately, some companies feel the need to make changes to their stuff, to be 'just a bit different' from the rest, which makes it incompatible, in far too many cases.
If you don't plan to disconnect the speaker wires on a regular basis, don't bother with any kind of plug- they aren't necessary and they don't "add" to the sound. IMO, they cause more problems than they're worth in too many cases- they increase the needed depth for the receiver or amp in a cabinet, they can be bent if stressed by wires pulling up/down/right/left, they can short, they can pull out and the wires can come out due to vibrations.
Banana plugs were never designed to be used when equipment would be connected and left alone for long periods- they were designed for convenience in applications that required quick connect/disconnect, like test labs, commercial/industrial and they NEVER used gold plating until the audiopile market told people they were Lepers if their plugs didn't have some kind of pretty plating, a story behind them and some kind of endorsement by someone who is to be believed in everything they say.
