In terms of calibers, they definitely offer everything in common use, along with a few in much less common use. I suppose someone must be buying those "boutique" calibers if they are still being made. They also offer them in various sizes and with some other selections/features like the MOS models, if that is what you are into- and all based on the same mechanical principle, with a huge overlapping in parts compatibility, regardless of model or caliber. Boringly reliable and easy and economical to work on if required. In worldwide use too. Whether you like them or not, there is no denying that Glock is a huge success story in handguns. Probably the biggest since JMB.