Bellco stainless steel probe holder is designed to be used with our 45mm blue polypropylene open top caps and white silicone gaskets. A wide variety of fittings are available to allow ph and do monitoring via insertion of these probes into the sidearms of the vessels. Threaded probe adapters are designed to allow introduction of threaded probes into vessels through 200mm stainless steel headplate or a 45mm vertical sidearm. 316 l stainless steel Polypropylene caps Autoclavable 13.5 thread for ph and do probes