Having clips on the bit end of your driving lines is risky business. Not only can it be a safety issue, but it can be very annoying to your horse, metal on metal is very irritating for some horses.
Why are they a safety issue? I have witnessed a draft horse that turned his head to bite at a fly and got the driving line clipped to his harness. It was not a pretty outcome once he realized he was stuck.

So, if your driving lines have a clip from the line to the bit, please just remove it and attach your lines directly to the bit.
A couple of these photos look like conway style buckles. I really recommend not using conways on the reins as they might slip and that would be bad. A regular buckle end is the best solution and much easier to put on and off than a conway.
Thank you so much Leslie! I have actually just recently talked with the harness shop and we agreed that we needed to change all the driving line buckles to the roller buckle style. I agree with you that conway buckles are not safe!
Mindy~
When driving they are not called rains but lines. just my 2 cents.
Yes exactly! They are referred to as lines when driving 🙂