Today these clocks and other variants are a retro-fashion. Also they were\are used a lot in bomb attacks and actually giving them an unfair bad reputation for being a terrorist watch. This couldn't be more unfair because any alarm clock can be used for a bomb, you just need how to connect it to the circuit. I'm not going to tell you :) Although you might already know. Don't bomb anyone please, and enjoy these little but awesome early 90's clocks.
Here you can se various variants of this clock. The one on the right is a Casio A158W and it's the one i use, the gold one on the is a A168 and belongs to my wife. The white one near to the F-91W is a fake Casio clock.
This clone stinks of fake as the LCD segments look different from the original Casio LCD, the beep alarm sounds different and even the display light mimics cheesy discoparty collored blinking lights.
I disassembled both and putted them side by side for comparison.
Here you can see the brains of the original Casio clock. Simple and elegant (apart the unevenly spreaded blobby epoxy over the IC).
Here is the fake one. Urgh!
I did a small video demoing both and disassembling them, showing some of the features!
Enjoy!