Bump. In my honest opinion, if a 490 is what you want, go for it. But know what you're looking for.
Buy these.
Not these.
The units with the grille on them are built by Shuntong (SNTOOM) who makes poor quality imitations of the original sirens and pumps them out to other companies who resell them for significantly lower prices compared to genuine units. They aren't durable and use motor components that probably shouldn't be used in motors.
SNTOOM also makes 590, 690, and 790 clones. They can be distinguished from their original counterparts by the number of screws they have on the front of the stator (Genuine 5 and 690s have 3, SNTOOMs have 4. Genuine 790s have 4, SNTOOMs have 5.)
Genuine 490s (and any other genuine MS for that matter) work fine and last a good long while.