A posture collar is a rigid collar

Collar (BDSM)

In a BDSM context, a collar is a device of any material placed around the neck of the submissive partner. It is also a term used to show ownership of one partner by another. A person wearing a collar to symbolize their relationship with another is said to be collared...

 that is wide enough to restrict movement of the neck

Neck

The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...

. Posture collars help in maintaining posture

Neutral spine

A neutral spine or good posture refers to the "three natural curves [that] are present in a healthy spine."- Posture :The word "posture" comes from the Latin verb "ponere" which is defined as "to put or place." The general concept of human posture refers to "the carriage of the body as a whole, the...

 by keeping the chin high and the neck extended. Posture collars typically flare widely at the front to reach from the chin

Chin

In the human anatomy, the chin is the lowermost part of the face.It is formed by the lower front of the mandible.People show a wide variety of chin structures. See Cleft chin....

 down to the collarbone, preventing the wearer from hanging their head or looking downward.

Such collars are typically made from leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

, but may also be made from metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

, rubber

Rubber

Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

 or plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

s such as PVC

Polyvinyl chloride

Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...

. Posture collars are often decorated, and may include other bondage

Bondage (BDSM)

Bondage is the use of restraints for the sexual pleasure of the parties involved. It may be used in its own right, as in the case of rope bondage and breast bondage, or as part of sexual activity or BDSM activity.- Private bondage :...

 elements such as locking closures, decorative spikes or D-ring

D-ring

A D-ring is an item of hardware, usually a metal ring shaped like the letter D. It may be used at the end of a leather or fabric strap, or may be secured to a surface with a metal or fabric strap...

s for attaching restraints.

Special type of posture collar is a neck corset

Neck corset

A neck corset is special type of corset which is worn fitted around the neck instead of around the waist as of with ordinary corset...

.