View Larger Image First In the World Kerotest invents, patents and introduces the world’s FIRST hermetic bellows stem seal device, the HSS, for rotary, quarter turn flow control devices. KerOTest34562019-01-04T15:14:14+00:00November 19th, 2018| Share This Story, Choose Your Platform! FacebookTwitterRedditLinkedInWhatsAppTumblrPinterestVkEmail About the Author: KerOTest3456