Silicone Pet Tag Silencers.  Keep tags from jingling, clanking and clinking together!  They also protect the tag from wear, so tags last much longer.  These fit tags in with the following sizes:
Bone: 1 9/16” W x 1 1/16”H (Lobo Commander Large Bone Size)

Circle: 1 1/4"W x 1 1/2"H (Lobo Commander Large Circle Size)