This is a puzzle bracelet which comes in a pair of identical parts. You can slide the two parts together until it makes a large oval through which you can push your hand. You then slide the two parts back in the other direction until a detent holds it snugly on your wrist, if of course it is the right size: this movie
https://richard-parkins.free.nf/exb2.avi on my web page at
https://richard-parkins.free.nf/ shows how it works. The model is available in four sizes which should cover the normal range of hand sizes. Each version is named EXB_pp_ww_hh, where pp, ww, and dd are the dimensions of the hand that it fits in millimetres. pp is the width of the opening through which your hand has to pass: this is the maximum width of your palm with the thumb at the side of the fingers (rather than folded underneath). ww is the width of your wrist where the bracelet will fit. hh is the height of the opening through which your hand has to pass: the maximum height may be at your wrist or over the ball of the thumb depending on how big the ball of your thumb is. If you have access to something like a bench vise, set the position of the jaws so that you can comfortably slide your hand between them all the way up to your wrist and then measure the distance between the jaws. For the bracelet to fit, the numbers in the model must be at least as big as the corresponding dimensions of your hand, and the wrist width should not be too much bigger, otherwise the bracelet won't be held firmly in place by the detent.
All measurements should be made with the hand sliding freely with no deformation of the flesh. If you need a size that isn't offered, use the contact seller button to ask me to make one: there will be a small up-front fee for the design work.
The prices shown do not include shipping or taxes: these will be added by Shapeways at checkout. If your delivery address is not in the USA or the EU, taxes may be payable on importation. For details see the Shapeways Shipping FAQ at
https://support.shapeways.com/hc/en-us/sections/360003556034-Shipping.
This model is characterised by Shapeways as First To Try, but has been successfully printed in brass. The brass version is available for sizing purposes only: I don't recommend wearing it because brass oxidises and isn't suitable for long term contact with the skin.