The Model 670 Pressure Chamber Instrument is unique due to the large chamber. The chamber is 4 inches in diameter and 7 inches deep. We only recommend this instrument if you are working with a large leaf since it takes a large amount of nitrogen to fill the chamber and makes working with smaller samples time consuming. This instrument comes standard with a Compression Gland Sealing System fitted with a 1/2 Inch Compression Gland Gasket and Insert. This gasket will seal samples from 1/2 inch diameter down to 3/8 inch diameter. Other sealing options such as bladed grass or other semi-round sizes check our other options are available.