These tissue grinders are capable of reducing cellular tissue to primary cells. Glass tubes are made of precision borosilicate glass. The Pure PTFE plunger head is threaded onto a 6.5 mm stainless steel shaft. Grinding chamber clearance is 0.15 to 0.25 mm. What's included: plain tip plunger (order glass vessels separately). plain tip plungers effectively homogenize a variety of tissue samples capable of reducing cellualar tissue to primary cells plunger head is Pure PTFE with 6.5 mm stainless steel shaft.