Measuring for Fit

Rigid steel does not forgive a guess. A soft cuff will stretch two centimetres and hide the error; a machined shackle will not. Five minutes with a tape gets it right first time — and if you measure before breaking the hygiene seal, a wrong size is still exchangeable.

What you need

A flexible tailor's tape, or a strip of paper and a ruler. Work in millimetres and write the numbers down. Measure at rest, at room temperature, and ideally at the time of day you expect to wear the piece: limbs are measurably larger in the evening, in heat, and after exertion. Measure the person who will wear it — wrists differ between people far more than clothing sizes suggest, and between a person's own left and right.

Where to take each measurement

Wrist. Around the narrowest point, just below the wrist bone on the hand side of the joint — the hollow where a watch settles. Keep the tape level and snug against the skin, not tight enough to compress it. Take both wrists.

Ankle. Around the narrowest point, just above the ankle bone. Same principle: against the skin without denting it. If you intend to wear socks, measure over them.

Neck. Around the base of the neck, where a collar rests above the collarbones and below the larynx — not high on the throat. Keep the tape horizontal all the way round; one that rides up at the back reads short. Head neutral, breathing normally.

Clearance

The measured circumference is not the size you order. Restraints need room, and the room is measured in fingers.

Wrist and ankle: one to two fingers should slide flat between metal and skin, all the way around.

Neck: two fingers, always. Never less, whatever a piece looks like when snug. A collar sits against a structure containing an airway and major blood vessels, and two fingers is the practice for a reason.

If you fall between two sizes, take the larger one. A restraint that is slightly generous still restrains; one that is slightly tight is a circulation problem waiting for the wrong evening.

Our ranges

• Oath Wrist Shackles — [PLACEHOLDER: adjustment range in mm]
• Oath Ankle Shackles — [PLACEHOLDER: adjustment range in mm]
• Sovereign Locking Collar — [PLACEHOLDER: sizes and internal circumference in mm]
• Eclipse Slim Collar — [PLACEHOLDER: sizes and internal circumference in mm]
• Vantage Rigid Spreader Bar — fixed 60 cm between anchor points
• Meridian Adjustable Spreader Bar — 65 to 95 cm, adjustable in [PLACEHOLDER: increment]

Spreader bars are sized by span, not anatomy. The 60 cm Vantage sits near shoulder width for most adults and is the safer starting point; the Meridian's range extends well past comfortable for many people, and its usable span is set by hip and shoulder mobility rather than by the bar.

Checking the fit in use

Once a piece is on:

• Slide two fingers under it. If you cannot, it is too small — take it off, do not proceed.
• Check circulation every ten to fifteen minutes. Press a nail bed until it blanches, release, and watch: colour should return within about two seconds.
• Stop immediately for numbness, tingling, coldness, or a hand or foot turning pale, dusky, or blue. None of these are worth tolerating for a few more minutes.
• Keep the metal on the narrow part of the joint. Restraints that ride up onto the forearm press on nerves the wrist does not, and nerve compression can outlast the session by weeks.
• Keep keys and blunt-nosed safety shears within arm's reach, and never leave a restrained person alone.

Fit is the part of this equipment that does the safety work. The rest is finish.