Hey all,
I had purchased a pair of Bingfu mag-mount antennas with the typically long name in the Amazon listing for use with my GMRS radios. Amazon currently lists this as "Bingfu Dual Band VHF UHF 136-174MHz 400-470MHz Ham Radio Magnetic Base Antenna Handheld Two Way Radio SMA Male Antenna for Ham Radio Walkie Talkie Icom Yaesu Vertex Standard Horizon Marine VHF Radio", on that package as-delivered it was listed as "Bingfu Dual Band VHF UHF 136-174MHz 400-470" and it has a barcode X002PKBG57. The Amazon listing is here: https://www.amazon.com/dp/B08N9W5GPV
Anyway, When I first got the radios and these antennas I did some testing, we managed 3200' in suburbia with the antennas that came with the HTs while sitting inside of the vehicles, but we only managed around 2000' with these mag-mounts.
Subsequent to that test I've acquired an SWR meter and some miscellaneous connectors so I was finally able to hook a radio, meter, and antenna with as few adapters as possible. SWR on one antenna was 2.66, and on the other was 2.83.
Suffice it to say, no good for GMRS, despite the frequencies advertised in the listing.
Since I have a 2m HT I may test SWR with that, just to see if they're any good at all on 144MHz, but I do not have high hopes.