It is a Forest River Tracer and the large slide-out has cable. Where those cables insert through the camper there are pieces of rubber that I've been told are a leak seal. Sorry...cell is not working so cannot take pics but the are about 1 x 3 inch pieces of rubber.
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
Funny you should ask that as I've been doing some research and I can find cable grommet....perhaps what's on the camper is a DIY replacement. Phone is working temporarily so I'm going to take a picture and post momentarily.