Simple concept, big hit! Tuchis TAG loves this one as he is a big chewer of sisal. All holes of the plastic baseball have a double knot of 3/16" sisal sticking out of them except the top and bottom. 2mm chain, 3.5mm wide jaw quick link, and washers are all stainless steel. The pictures depict what it looks like before the bird chews on it and what it looks like after.