Ruffwear Doubleback Full Body Safety Harness Gray Red Rock Climbing Size Small. The Doubleback™ Harness is a full-body dog lifting harness. It's a strength-rated belay harness that opens up new areas for dogs to explore with their humans that would otherwise be difficult to access. Strength-rated to 2,000 lbf or 8.9 kN, the Doubleback Harness is designed to be comfortable while aiding in lifting and lowering dogs in exposed areas, meaning your furry buddy can tag along when the climb gets steep.