... heater. Usage:lighting, test tube Borosilicate glass tube 3.3 OD: 3mm~320mmColor: Clear / blue,green,yellow, purple, pink, red, black, milk-whiteTube ends ... , ground, rough Description:Material: high borosilciate glass 3.3Feature: heat-resistant, anti-acid, anti-alkaliApplication: Lab glass ware, solar vacuum tube, lighting, handcrafts