Barrel nut

They are preferred over a standard nut and bolt, because they do not require a flange to be machined or forged onto the receiving part, thus reducing weight.

[1] Furniture cross dowel barrel nuts are cylindrical shaped metal nuts (metal dowels) used with furniture connector bolts to join two pieces of wood.

The inside threaded hole is unusual in that it passes through the sides of the dowel.

The furniture connector bolt is then inserted into the bolt hole and screwed into the cross dowel until the wood pieces are held tightly together.

Barrel nuts are also common in flat-pack furniture, where long bolts and barrel nuts are used to hold together T joints in chipboard sheets.