Carrying and storing pocket knives: all sheaths, cases and knife bags

In practice, nothing: both protect you and the knife. You hear "sheath" more often with fixed knives, and "pouch" or "case" with pocket knives and multi-tools. We use the terms interchangeably.

No. Some are made for one specific model, such as kydex holders for multi-tools. Choose the rest by size: measure the length of your closed knife and compare it with the size shown on the product page.

Measure your knife when closed, from end to end, and choose a size just larger than that. If you are between sizes, choose the larger one: a knife that fits too tightly is hard to draw with cold hands.

Leather is quiet, feels pleasant and develops character the longer you carry it. Kydex clicks audibly into place, holds its shape and lets water and sand drain straight out. If you carry your knife outdoors in the mud, kydex is more practical.

Keep it dry and rub in leather grease or a thin layer of bees wax a few times a year. Got it wet? Let it dry at room temperature, never on a radiator, as the heat will warp and harden it.

Yes. Clips such as the Tek-Lok fit most kydex holders and can be screwed on yourself. This lets you decide whether your knife hangs straight, at an angle or horizontally on your belt.