Triangle Trio is a wooden puzzle designed and made by William Waite.
The five pieces are made of different combinations of the circles and you have to try and fit these within the frame. There are three possible solutions but finding all three is really quite a challenge.
One solution is given on the back of the frame but you are on your own finding the two others.
Handmade in the US from Red Alder and Black Walnut, this measures 10 x 9cm.