These 15mL capacity PYREX® tissue grinders (homogenizers) are recommended for soft tissues found in the liver and brain. They are designed to handle both initial grinding and final homogenization in the same sequence of operations. Mortar is not ground and the pestle contact surface is Polytetrafluorethylene (PTFE), threaded onto a stainless steel shaft. -Caution: If used with a motor-driven device, the attachment must contain some form of friction release clutch to prevent damage to the apparatus from pieces of connective tissue or muscle. The user should wear a protective glove of sufficient thickness to prevent injury in the event of failure of the glass components. These 3mL capacity PYREX® tissue grinders (homogenizers) are recommended for soft tissues found in the liver and brain. They are designed to handle both initial grinding and final homogenization in the same sequence of operations. Mortar is not ground and the pestle contact surface is PTFE (PolyTetraFluoroEthylene), threaded onto a stainless steel shaft. -Caution: If used with a motor-driven device, the attachment must contain some form of friction release clutch to prevent damage to the apparatus from pieces of connective tissue or muscle. The user should wear a protective glove of sufficient thickness to prevent injury in the event of failure of the glass components.