I had to throw away all three in a few weeks, because all after a relatively short time while driving with the unit (but wirelessly activate alarm) the electronics are burned through. Maybe it was because I used 9V battery. The radio receiver of the remote activation consumes noticeable power, so that the battery is empty after about 1.5 weeks "standby". Therefore, operation without battery hardly seems sensible.
That's really a shame, because the parts are pretty loud and the De / Activation via radio works great. The sensitivity may be somewhat lower in my opinion, but better this way than the other way. The remote control is even coded individually to the receiver, so you can use more than one of the parts in parallel!
Only the magnet for holding is much too weak for a bicycle, and most motorcycles. It helps a lot if you just attached to the frame as a counterpart a powerful neodymium magnets or simply using a Velcro strip. The housing is not waterproof, so you should install the thing in a protected area or in a small bag.
Conclusion: It could be a great part for the price, but if three times in succession always scorches the same part innendrin, then the worm is inside. I can therefore not recommended.
