In Dr. No, an FBI agent is astonished to find a gun hidden in Bond’s inner jacket pocket and asks, “Where were you measured for this, Bond?” Bond replies, “My tailor, Savile Row”. The point is that in a well-constructed suit jacket, you can hide and disguise a lot inside the inner pockets.

The number, positioning, and dimensions of inner pockets can vary vastly depending on the jacket’s construction. Traditionally, a jacket will feature at least two inner pockets behind the lapels—one on each side—along with a pen pocket and an additional lower hip pocket on the left. On bespoke garments, unconstructed jackets, and jackets for more formal occasions, other configurations are often preferred.

Inside pockets, of course, serve a practical function. They are designed to meet the needs and habits of the wearer, evolving over time to accommodate changing lifestyles. While there are no strict rules, there are both historical traditions and modern adaptations in pocket design. In the early 2000s, as MP3 players became popular, suit designers adjusted the dimensions of inner pockets or repurposed them to accommodate these new devices. Nowadays, insides pockets commonly hold a smartphone and will be adjusted to its size.

The right inner chest pocketsmall front left pocket located at armpit level - on a jacke, often equipped with a button for added security, typically holds a wallet or cardholder. The left chest pocket, frequently slanted, historically is used for items such as notepads, tickets (if there isn’t also an external ticket pocketsmall piped pocket with flap above the right pocket of a jac), or other essentials. Below the left inner chest pocket, you will often find a smaller, vertical, slanted pocket, which traditionally carried a fountain pen. An additional pocket near the bottom left side is ideal for glasses or, indicative of its size, a cigar box.

Pocket style also varies between welted, slanted, patch, or even zipped designs, and depends on personal preferences. There are, however, some rules in terms of construction: on a fully lined jacket, inner pockets should always be set into the main fabric to ensure durability. Bar tacks at the pocket openings strengthen the fabric, preventing sagging and ensuring the pocket maintains its shape over time.