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GripStrips Anti-Slip Treads - 8 Pack, Black (32" x 2") - Outdoor Non-Slip Tread Strips - Waterproof Safety Traction Strips for Stairs, Ramps, Boats, Ladders, Wood, Concrete, Metal - - Amazon.com
Ramps.org - Ramp Features
What to Use on a Wood Ramp to Prevent Slipping | Hunker
Anti-Slip Walkway and Ramp Covers - Safeguard Technology.