A chain is only as strong as its weakest link, so it is worth getting the right one for the job. The most common and original form of protection. Although they may seem simple, there is more to these lumps of metal than at first glance. They are highly engineered pieces of equipment. Also each book and video has a small review.
Cams are the most useful pieces of protection.
It is a pity they are also the most expensive. Find out how they work, why they work, and more importantly, which ones are best.