this question is asked quite often.
slide supports are holdovers from the early days of slideouts.
now, the technology doesn't need them, in fact you should have something posted or in your manual, warning you NOT to use them.
most manufacturers will void the warranty if you do.
there are many threads about this on the forum.
a simple search will give you lots of reading on the subject.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity