May depend on the manufacturer of the RV. A customer service tech at Winnebago told me it wasn't necessary to use them.
58,000 miles and I have not used them.
Clay (WA5NMR), Lee (Wife), Katie & Kelli (cats) Salli (dog).
Fixed domicile after 1 year of snowbirding and eleven years Full Timing in a 2004 Winnebago Sightseer 35N, Workhorse chassis, Honda Accord toad