Boston round clear Type III glass bottle. Caps for 125 mL and 250 mL sizes are ultrasonically bonded with a .125" PTFE-lined silicone liner. Caps for 500 mL and 1000 mL sizes are equipped with a friction-fit PTFE liner which is easily replaced if necessary. Polypropylene closure. Excellent for water sampling. The I-Chem® 300 Series bottles include full laboratory certification. I-Chem® 200 Series bottles are prepared to the same specifications as the 300 Series and are available with a certificate upon request. I-Chem® 100 Series bottles are made of the same quality materials and to the same specifications as the I-Chem® 200 & 300 Series jars. However, these products are neither processed nor certified.