Stainless steel Boston cocktail shaker, a professional-grade bar tool.
It features a two-tin design (one large, one smaller) for a spill-free, watertight seal when mixing drinks.
The design is favored by professional mixologists because it does not freeze shut when shaken with ice, unlike some other shaker styles.
It is typically made from durable, rustproof, and anti-corrosion stainless steel.
A separate strainer (like a Hawthorne or Julep strainer) is required to pour the liquid cleanly.