A Samsung handset named GT-I9405 has leaked on shipping notes. The unknown device has a 5.5-inch screen and a single SIM. At the moment that's all that's known of this new handset.
The puzzling part is that this code sits between the Galaxy S3 (GT-I9305) and S4 (GT-I9505). But despite being apparently in between the two, this device has a larger 5.5-inch screen than the S4's 5-inch and S3's 4.8-inch screens. In spite of the size increase it's not a Galaxy Note as their codes start with NT.
We've seen several leaked shots of the new Samsung Galaxy Note 3 Lite, or Neo. This is a 5.5-inch device but has the code SM-N7505, so this device isn't that either.
So, short of guesses, telling you what it's not is about as much as we can do right now. But expect more details to follow as we dig deeper.