The trays / caddies have been removed from a working system (e.g. server). These products vary in their usage due to age of system & type of service etc. Our technicians take a lot of care in their refurbishment.
However, Used System Pulls are fully tested and all handling is performed by trained technicians, taking full ESD precautions.
Kindly note that for Dell servers and storage systems, the HDDs physically fitting into the servers have nothing to do with whether or not the caddies are cross-compatible. The bay that accommodates the HDD will be the same size across the caddies, but the caddies themselves are not any kind of industry standard size. Most caddies will only work in one particular system.