String spreaders are simply a device that raise and lower the main strings in a tennis racquet during the cross string installation procedure.

The pair shown below are mine that have been in service for over thirty (30) years, therefore, the well-used look!  There are a number of devices available but what are they really used for?  Some of the latest versions say they are to assist beginning stringers in the weaving process.  This has elicited comments from longtime stringers that "I don't need any help.

I trust my weaving skills".  Good, because weaving is the least important function of string spreaders for beginners or long-time stringers!

Stiction and friction reduction is the most important function of string spreaders, and it is an important function that is most often overlooked.

So, if you want to try string spreaders for your clients racquets use them to enhance the string bed and not to relieve you of proper weaving technique!