Specification Brand : Dukal BulletPoint1 : Pack of 75 BulletPoint2 : Highly Efficient BulletPoint3 : Easy to Use BulletPoint4 : Country of origin: China BulletPoint5 : Capacity : 600 milliliters Color : Silver ExternallyAssignedProductIdentifier1 : 0779675550799 ExternallyAssignedProductIdentifier2 : 779675550799 IncludedComponents : Swabstick ItemName : Dukal DUK 864 Lemon Glycerin Swabstick (Pack of 75) ItemPackageDimensions_Height : 6.46 inches ItemPackageDimensions_Length : 17.72 inches ItemPackageDimensions_Width : 11.73 inches ItemPackageQuantity : 1 ItemShape : Square ItemTypeKeyword : science-lab-swabs Manufacturer : Dukal Corporation Material : Wood ModelNumber : 1157R16BX NumberOfBoxes : 1 NumberOfItems : 75 NumberOfPieces : 4 PartNumber : 1157R16BX ProductDescription : Single Valve Bag It's a sampling bag with only one valve installed. Double Valve Bag It's a sampling bag with two identical valves installed on it. The inlet and outlet of the single valve sampling bag pass through one valve Differences One valve of the double valve sampling bag is inlet and the other is outlet. The advantages of the double valve bag are: several small capacity air bags can be connected in series to form a large gas sampling bag; and one in and one out is convenient for cleaning the gas sampling bag