ProGrip Surface Mount D-Ring- bolt on design, light duty rated to 1200 lb break strength, 400 lb working load limit, medium duty is rated to 5,000 lb break strength, 1,666 lb working load limit. Light duty is sold as a 4 pk, medium duty is a 1 pack. Bolt on designLight Duty 1200 lb break strength400 lb working load limitSold as a 4 packMedium Duty5000 lb break strength1666 lb working load limitSold as a 1 pack