Counter Surveillance | RF Signal Detector | Bug Sweeper | BH-04 Professional | FCC & ICES Certified

the description of the item on the product page is very detailed and describes the product well. it's a pretty specialized device, so if you need one you'll likely already understand most of the specs. i first encountered the i4 technology company via their bh-03, the previous model. that one and this one are at about the top tier in pricing for these types of specialized devices before you jump several thousands dollars to a more 'professional' model, but to do that you're likely already working in the genre.thus, the bh-03 seemed expensive when comparing with other such devices, but you had to dig below the surface to discover the amount of tech that went into a device about 2/3rds the size of a pack of cigarettes and even though the size of the bh-04 expanded, it is still very thin and will fit in a man's shirt pocket despite now having two antennas to support the two 'channels' or frequency ranges. this allows for much more flexibility and anyone who knows any rf theory can remove either antenna and replace it with one specific to the band or frequency range they expect to be looking for.the bh-03 has a fixed, telescoping antenna and replaceable batteries and the new bh-04 has replaceable antennas and a fixed battery pack charged via usb. ideally both would be replaceable because it's easy to snap off the antenna on the bh-03 and eventually, with daily usage the battery pack in the bh-04 will start to decline in efficiency and i doubt it's user replaceable. on the plus side, it seems to last forever as i've had mine for over two weeks with it mostly on as i consulted the manual and still have a full charge icon. also, you can use it while connected via usb.one thing to be aware of on the bh-04 is that they moved the power switch to the side and it sticks out from the case and doesn't take a long hold to power on making the ability to put it in a case problematic unless perhaps you put a piece of foam to stand the switch off from the side of the case--it would be easy enough to put a hole in a piece of foam and cover the switch when putting it into a case.of the differences, the most striking must be the display which now must display two channels at once if you have them both activated and it does a great job with contrasting colors and, unlike the bh-03, you can see it outside if you can get out of direct sun. it displays a _lot_ of info in such a small space. also, the new oscilloscope mode takes advantage of the new display to show waveforms of received signals which helps tremendously in analysis and the screen can be 'frozen' with just a button push.another great feature for those needing it is that if the signal is outside one of the labeled tag ranges such as gsm, wifi, 3g/4g it will display the received frequency although slightly rounded from the exact frequency some of the time. btw, it covers the 5g frequency range, but this isn't clear to those who wouldn't know because only the product page on the i4 website mentions it and it's unclear as to whether there's actually a 5g tag or label. i couldn't get one to show using my iphone connected via 5g. also, hardly any device covers the ultra short range milliwave (?) 5g which i believe is around 25ghz.like the bh-03, it's very easy for an absolute beginner to use the device. they turn on in /search/ mode and sets appropriate levels and you can also zero out interference with one button. you can also manually set levels using the up/down arrow keys. there are now external volume up/down buttons on the side which is very handy. another great feature (which must have been added at the request of those who have to write reports on what they found) is its ability to log and for the user to be able to copy the log files to a pc just by plugging in a usb cable.all in all and despite this model being nearly twice the price of the bh-03, they added a lot of value to it and future-proofed it to the point it competes more than favorably with the competition (i feel it surpases the competitors) until you jump to nose-bleed prices of devices which are basically full-blown spectrum analyzers./guy (73 de kg5gt | wqpz784)