Custom U bolts are a daily routine for us and this is a 5/16-18 threaded U bolt we supplied a customer, made in the USA using 304 stainless steel material with plain finish. It measures 4-5/16 inches on the inside width and 5-1/2 inches on the inside depth. The customer was in a big rush and we were able to get the parts made and shipped within 3 days from order. Material certs were provided as well per our customer's request.