Metal rock nut with thick silver metal cable. The nut is tapered and hollow with the cable extending through the entire nut. There is a neon green sticker within rubber wrapped around the bottom of the cable.
All the stoppers included in the donation were used all the way up the Dawn Wall climb as climbers will use the same gear on every pitch of the climb, placing it as they go up, and removing it when they've finished to use it on the same pitch.
Tommy Caldwell was born in Colorado in 1978 and is best known for completing the first "free" (meaning no rope assist) rock climb of the Dawn Wall of El Capitan in Yosemite National Park in California. Caldwell is an advocate for protecting the environment and is an active member of the non-profit group Protect Our Winters, a group that seeks to combat climate change.