This stainless steel thermowell is your best option of monitoring temperatures in the 27L or 55L FermZilla. Since the thermowell installs into the lid, the thermowell will be well positioned in the middle of the fermenter to provide an accurate core temperature reading. On the bottom side of the FermZilla’s lid you’ll find several convenient drill locations already molded into the plastic. The thermowell is long enough to work with either size FermZilla (or other fermenters) 23.6 inch long (60 cm) 516 inch OD (8 mm) 14 inch ID (7 mm) Made from 304 stainless steel