Here, we‘re talking about weight and type of "container". The most common weight is 2oz/50g. Some tobaccos are also availabe in double, far fewer in half, that quantity. Tobaccos are generally sold in bulk (or loose), in a plastic pouch, or in a tin. Due to cost, weight, and size, tins are not as commonplace as pouches nowadays. As for bulk/loose tobaccos, and depending on the shop, the desired quantity is usually sold in a transparent, plain, plastic pouch that can keep up to 50g of tobacco for a week (with about 3-4 pipefuls a day), with no risk (we‘re not talking about capacity now, rather the functionality). For bigger quantities, we recommend a jar that seals the tobacco in. The plastic pouch can be used for 50g at a time.