Fall protection equipment manufacturers are innovators. They are constantly developing new types of equipment and upgrading the capabilities of existing equipment. Self-retracting lanyards (SRLs or ‘yo-yos’) provide a great example of this innovation. 

Legible labels on SRLs are essential to determine if they are the right for the job.
When self-retracting lanyards (SRL) were first invented decades ago, they were generally only used in a manner that restricted the freefall to two-feet or less. In other words, the SRL was anchored overhead. But as these devices became more popular, many employers began using them in a variety of ways which, in some cases, was outside of the manufacturer’s limits. An example would be using an SRL when working on a leading edge (a leading edge is an unprotected edge that is under construction which means that it is changing position as is it being built).

When you anchor the SRL back from a leading (or unprotected edge) and the worker falls you have two problems. First of all the freefall would be more than two feet (probably about five) and there's a chance the SRL would fail. Secondly, you would be dragging the lanyard over a potentially sharp edge and exposing it to cutting action especially in cases where there was a swing fall.

In response, the equipment manufacturers began to build additional classes of self-retracting lanyards. Currently the following types are available: