I was worried that the holes would be too small for any chain to fit through them, but I was able to find these silk cords&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Black-Silk-Cord-Chain-Bracelet-Antklet-Necklace-with-Sterling-Silver-Clasp-7-8-9-10-12-14-16-18-20-22-24-30-36/dp/B002WALVNG/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Black Silk Cord Chain Bracelet, Antklet, Necklace with Sterling Silver Clasp 7 8" 9" 10" 12" 14" 16" 18" 20" 22" 24" 30" 36"</a>&nbsp;that fit perfectly through the holes.  I bought these for my cats to wear and they are a perfect fit.  Not too big and not too small and they love them.