A part of the mucosa on the hemorrhoid is cut off from the blood supply by a rubber band, so that it necrotizes and - often unnoticedly - falls off after a few days. The cicatricial fibrosis causes a reduction of blood supply for the rest of the hemorrhoidal tissue.
The base of the node is sucked into a small cylinder, onto which the rubber band was put. A second cylinder pushes this ring above the sucked in node.