There are currently two major manufacturers in the US for that kind of lock down system. One is EZ Lock and the other is Q'Straint. The brand and model will typically be somewhere on the locking device.
I have an EZ Lock. To use it, the wheelchair must be equipped with a "bracket" sold by EZ Lock. That bracket is threaded for a 5/8" coarse thread bolt. One of the appropriate length is screwed into the bottom of the bracket and that bolt is the one folks, including me) complain about tearing up thresholds (and other things).
I have 3 wheelchairs with EZ Lock brackets and they all take a slightly different length bolt. I use the shortest bolt that will still engage with the EZ Lock base installed in the van.
I have one wheelchair (an F5 bought used) that came with a Q'Straint bracket. It works the same way as the EZ Lock, including using a 5/8" coarse thread bolt. The bracket on that wheelchair just barely makes it over the EZ Lock base installed in the van, but it does work.
On my C500 wheelchairs, the EZ Lock bracket places the bolt close to inline with the drive wheels. This allows the drive wheels to lift the bolt up and over a threshold if the threshold is approached head on.
I have heard that on the EZ Lock bracket for the F5, the bolt is placed much further aft of the drive wheels, making it catch on many more things.
I have heard the Q'Straint bracket for the F5 places the bolt further forward than the EZ Lock bracket, but still aft of where it is on the C500 EZ Lock bracket.
You can sometimes find used EZ Lock and Q'Straint brackets on ebay. Be careful, though. There are at least different versions of the Q'Straint bracket depending on whether you enter the lock from the front of the vehicle (wheelchair rolling backwards) or the rear of the lock (wheelchair rolling forwards).
Steve