Link and round link metal chains are differentiated by whether they are welded or unwelded, the latter version also being referred to as decorative chains. In the case of the welded versions, the opening of each individual link (which is located along the length) is welded together, which automatically means that this class of chain can withstand greater stress than the unwelded versions whose links are indeed closed but can still be bent open in order to link the ends together or to hang something on a link. Aluminium chains are, according to this criterion, likewise decorative chains because, being aluminium they are unable to be welded, which leaves their links open (to bending!).
Chains are additionally divided into groups according to the shape of their links: Type A are short linked chains whose links have a shorter length (widths being equal) - the A links, then, are somewhat rounder in shape than those of Type C, whose links are more stretched out and, widths being equal, are in fact simply longer. There are all sorts of other types of chains ring chains, chandelier chains, knotted chains, band chains and even more but none of them have yet made it into our assortment.
Next up is how to understand the given dimensions for individual chains.
This way of giving the measurements has the advantage that when knowing the length of a piece of chain it is easier to determine the number of links there are in that length because the thickness of the material of the links that are connected will not be counted twice at the point of overlapping, which would give a number larger than it should be. For example: a 50 centimeter piece of steel chain with the given dimensions 1.5 x 23.0 x 8.0 mm consists of 21.74 chain links (500 mm divided by 23 mm).