The inner cylinder normally supplied for the Model 35 Viscometer is the B1 bob, the standard for drilling fluids and cements and other applications as well. This bob is made of 303 stainless steel for good wear resistance and is hollow for neutral buoyancy, low rotational inertia and fast response in typical test fluids. Recommended maximum-use temperature is 200°F (93°C). Three additional bobs are available and are normally used with the R1 family of rotors.
