Parts of a Pocket Knife – Blades, Backspring and Liners

All 11 parts on the diagram

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Whole knife 6

Master blade The main blade, the largest on a knife with two or more.
Pen blade A small blade, first made for trimming quill pens.
Nail nick A fingernail groove used to pull the blade from the handle. It is also called a nail mark.
Bolsters Metal pieces at the ends of the handle. Some knives have one at the blade end only, and some have none.
Scales The handle pieces on the two sides of the knife. Made of wood, bone, stag, plastic or another material.
Shield A small metal inlay in the handle. It can carry the maker's mark or the owner's initials, or be there for decoration. It is also called an escutcheon.

Inside the handle 5

Tang The part of the blade between the two sides of the handle. The pivot pin passes through it.
Kick A projection at the tang's bottom. With the blade closed it rests on the backspring and keeps the edge off it.
Pivot pin The blade swings open and shut around it.
Backspring A strong spring along the back of the handle. It presses on the tang and holds the blade open or closed.
Liners Thin sheets of metal between blade and handle material. The scales and bolsters are fastened to them.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. (1) Wikipedia, text only, Pocketknife and Slipjoint, https://en.wikipedia.org/wiki/Pocketknife and https://en.wikipedia.org/wiki/Slipjoint (master blade, pen blades, nail nicks, tang, backspring, liners, scales, bolsters). (2) A knife retailer's encyclopedia of terms, https://agrussell.com/encyclopedia/k and its other letter pages (main blade, pen blade, nail mark, tang, kick, back spring, liner, scale, bolsters, and the shield under its other name, escutcheon). (3) Levine's Guide to Knives and Their Values, read as passages returned by the Internet Archive's full-text search, https://archive.org/details/levinesguidetokn0000levi (master blade, nail mark, tang, kick, backspring, liners, handle scales, bolsters, shield, pivot pin). (4) Lake, Centofante and Clay, How to Make Folding Knives, read the same way, https://archive.org/details/howtomakefolding0000lake (nail nick, tang, pivot pin, backspring, liners, bolsters, scales). Hints and detail lines are in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's knife, nothing traced. Licence: own work

How it works

The parts of a pocket knife on a two-blade folding one: master blade, pen blade, nail nick, bolsters, scales and shield. A second drawing opens the handle to show the tang, kick, pivot pin, backspring and liners.

Read the full guide

A handle built in layers

Each side of the handle is a thin metal liner with a scale on the outside and, on many knives, a bolster at the end. The blade sits between the liners and turns on the pivot pin, which passes through its tang. The backspring runs along the back of the handle and presses on the tang. The kick is the small step under the tang, and the nail nick is the groove near the back of the blade.

Tang and kick are both part of the blade: the tang is the whole end inside the handle, the kick only the step beneath it.
Liners are inside and scales are outside: the scale is the piece a hand touches.

Questions and answers

What are the parts of a pocket knife called?

On a two-blade knife: the master blade and the pen blade, each with a nail nick, a tang and a kick; the bolsters, scales, shield and liners of the handle; the pivot pin the blades turn on; and the backspring.

What is the backspring on a pocket knife?

A strong spring along the back of the handle. It presses on the tang and holds the blade open or closed. A folding knife that has a backspring and no lock is called a slipjoint.

What is the nail nick on a pocket knife?

A groove near the back of the blade for a fingernail, used to pull the blade from the handle. Some knife books call it a nail mark.

What is the difference between liners and scales?

Liners are thin sheets of metal on each side of the blade. Scales are the handle pieces fastened to the outside of the liners; they can be wood, bone, stag or plastic.

What is a pen blade?

A small blade, first made for trimming quill pens. On a knife with two or more blades the largest is the master blade, and the small second blade is often a pen blade.