Review on StarTech.com DB9 RS232 Serial Null Modem Adapter - F/F - NM9FF - High-performance, Reliable Data Transfer by Tyler Owens

If you have an RS232 adapter with a nut and need to properly connect it to the device, this is it. I found the screws on this one to be too short - took great pains to finger tighten them so they wouldn't fall out under their own weight + adapter. On my unit (Mikrotik CRS309) it might have been the feet, which can be swapped out if needed, but if the screws on this product were 0.5mm longer it wouldn't be a problem. I don't use flow control. in my app but others say the wiring might be weird - I wouldn't buy this again. It's also almost double the price of Monoprice's semi-permanent adapter, and you can get several slim adapters for a quick/temporary connection at that price (in my case, you just unscrew the MF nut from the center of the adapter). this one, it won't be as safe, but works fine).