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