THE DIFFERENT GUAGES:
Obviously, the thinner the guage, the more powerful the string, with lots
of spin potential. BUT...the string will be less durable, but you could allow
for that by going for a really thin, durable string.
Guage 17 (1.25 mm) is standard for squash and "thinner than normal" guage for tennis .
Guage 18 (1.20 mm) is "thinner than normal" for squash the thinnest guage for tennis.