These 9mm outside diameter, 6mm inside diameter straws are 9" long, the perfect height for a quart jar (32oz) or pint-and-a-half (24oz) jar. These straws are cut from glass tubing and the ends are polished by hand. Because of this, there can be small variations in the diameter. Glass straws are fun because you can see the liquid rising up through them like in a disposable straw. It is also easy to see if they are clean. They are made of clear borosilicate glass, which is shatter resistant and is the strongest type of glass available. They are very durable and will last a long time. They fit in 10mm straw holes, like our stainless steel and silicone lids, but not 8mm like our painted straw hole lids. The most reliable way to clean reusable straws is our straw cleaner with soap and hot water. They are also dishwasher safe, or a quick rinse might be sufficient. You can also boil these to disinfect them if you want to. My personal cleaning routine is to rinse them after use, put them in the dishwasher, then run a straw cleaner through them and rinse again before putting them away. My dishwasher usually gets them clean but sometimes leaves a little residue so this ensures they are clean. Every day, 500 million disposable straws are used in the US! Start being part of the solution instead of part of the problem! Glass straws are: * Beautiful * Reusable and long lasting * Eco friendly * Dishwasher safe * Safe for all types of foods and beverages * Free of chemical leach Note that jars and lids are sold separately. These straws are made of the strongest glass available, but all glass is breakable. Please be careful!