One of THE most important upgrades you can make on your RV is adding rollers to assist slide out wear bars. This video has some pointers on the fastener and their part in the roller system. Slide outs on this RV is by BAL Accu-Slide.
If at all possible, stainless steel fasteners should be used.
Link to stainless steel screws: https://amzn.to/3RPU7Dz

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