smallest proximity sensor

I was wondering what the smallest proximity sensor is. I have a DEI 508d but it is quite big. Googling on the net I have found the Omega/Crimeguard AU-94TM and AU-95TM. Based on size of connector and adjustment screws it appears smaller than the 508d. However, the specs say it is the same size. I wonder if the descriptions have been incorrectly copied from the description for an earlier model. All the AU-95TM descriptions also seem to steal the description from the 94TM even using 94TM throughout. If anyone could post measurements that would be helpful. I ask as the 508d is too big for my intended location, but a smaller unit may fit. Failing that I will use a glass break sensor instead. Thanks in advance.

There was a brilliant unit made by the South African firm Conlog. I installed it once with a Viper, we were out of 508ds and it worked perfectly.

What's big? My Steelmate uW is 69x60x14mm.

508d is 80x58x23mm (96mm long including mounting tabs)

Ok my new thought is to use the sensor out of it's case or even to make a custom case. The only feature of the case I guess is important is the foil backing on the bottom part of the case and the isolation of this from the back of the PCB to prevent shorts. I presume this foil deflects the microwaves uniformly. Is doing this likely to cause any problems?

Hoping the thread is still read (I know how annoying it is when people post multiple threads about the same thing instead of sticking to the same one, lol). Further to the above I have found one potential location to install by the sunroof motor underneath the motor cover, this would necessitate removal of the cover on the sensor, and removal of the emergency sunroof closing tool. This would be a great location in terms of ease of access in order to adjust. I would try and adjust it as soft as possible so it only just about warns away when a face and hand moves quickly outside the window, and full alarm when a head and arm enter well into the cabin. However, I am concerned that in this location the full trigger and warn away would extend past the front windscreen (as illustrated below), so it may warn away or worse fully alarm in conditions such as heavy rain. The other possible location is under a cup holder in the centre console precisely in the centre of the car between the backs of the two front seats, but that would be tricky to get to to adjust and would need sticking directly underneath. My other thought was to chuck the sensor in the bin and use a glass sensor instead. Any thoughts or suggestions welcomed. Thanks in advance :)

Ah yes the Golf Mklll factory alarm syndrome. Roof is still best for range and lack of obstructions, mind you there should be bags of space under centre, just don't leave any coins or keys above it.

By the way the foil is the ground plane so yes you can remove it from it's case as long as it has metal under it. The 508d is too high, the custom unit that comes with the G5 Cliffords is much smaller but only works with those alarms.

Thanks Howie, do you think at this position in the roof near the windscreen would false? If it might false I guess some possible solutions to reduce could be a wedge under the front part of the 508d, and possibly a metallised sunstrip/tint. Don't understand the reference to the Mk3 Golf alarm, but that happens to be someone else's Mk3 golf behind my car, and their alarm goes off regular, lol.

The UK factory alarms on the first 2 years of the Mklll were made for a VW subsidiary called Votex, actually manufactured by Cobra and they were nothing but trouble, i.e. false alarming every time it rained. The wedge idea is very good. the 508d is about 2 generations of Israeli designed intruder technology ahead of the Mklll VW units.