The Boston shaker has two parts: one stainless steel tin, and a glass tumbler that fits snugly inside. Boston shakers can also come in tin-on-tin varieties. This is one of the most common shakers you'll see behind the bar.
Boston shakers with a clear glass are beneficial, as it allows bartenders to see what they're pouring; this makes it easy to spot any potential mistakes. However, it can sometimes be difficult to create a proper seal if you're using the glass on tin variety, so be sure to firmly tap them together before shaking.
A cobbler shaker has three parts: the tin, a strainer, and a small cap. All of these pieces fit together to create one unit.
This cocktail shaker is compact and requires less equipment than a Boston or French shaker; no need to fish around for a strainer, as it's already built in. The cap can do double duty as a jigger if you're in a pinch.
While it is attractive, this strainer has a tendency to get stuck, so it's not recommended for new bartenders.
The French shaker is sort of a hybrid; it has the good looks of the Cobbler shaker, but the practicality of the two piece Boston shaker. This shaker is made up of two stainless steel tins. Much like the cobbler, this tin can be somewhat difficult to pull apart after shaking a cocktail.
This shaker is not commonly seen in bars, as you're more likely to see bartenders using the Boston shaker.
