What is that big orange knob on EMC Unity 600 series storage processors?

Question

There is a big orange knob on the storage processors, for example, see the following picture (which show storages equipped with two storage processors, therefore we talk about these, in total 4 orange knobs):

I can't find any document describing their function. Please explain it!

Answer 1

It is simply the handle you can use to remove the storage processor board;
the hardware information guide calls it a "torque knob" https://www.emc.com/collateral/TechnicalDocument/docu69319.pdf