The salt in these lamps come from the foothills of the Himalayas; the block of salt is shaped and then hollowed out inside to contain a bulb. These look beautiful when lit, they aren’t strong enough to be a sole light source by themselves but they do give a lovely atmosphere. The base on which these stand on are made from wood and are screwed into the base of the salt block, there’s a small gap to allow a cable through at the bottom.
A theory behind salt lamps suggests that as the lamp heats it, it gives off negative ions into the air which have health benefits. (There is some debate about this, however some studies have shown low levels are given off).
The sizing of these lamps is pretty constant, but you will find that their shape and colouring can differ, the quality is always constant.