do you guys sell extra hardware for them? I've lost a screw/bolt

Are you referring to the bolts/screws for the Spur Mounted Support? If so yes we can look to get you a replacement. This isn't a current item we stock but we can work with the manufacturer. Please shoot us a text at 920.347.440 with pictures of exactly what you are looking for. Or you can email info@arbsession.com.