Understanding Rail Fitment
The rails of your Peragon cover are designed to sit INWARD of your truck's bed rails, resting on mounting brackets/quick clamps, not on top of the bed rail.
By keeping the Peragon rails as far inward as possible, it leaves room for accessories like rails and rack systems, which often mount to the stake pockets. See articles below:
Sport & Headache Bars: https://peragon.zendesk.com/hc/en-us/articles/360052924473-What-Headache-Racks-work-with-the-Peragon-Cover-
The drawing below may not look exactly like your mounting system, but it helps illustrate that our rail design does not extend onto your truck’s rail very far, if at all. The seal on the outside edge of the cover will bridge any gaps and overlap about 1/2".
Installation Assistance
First, check to see that your rails are on the correct side. You will need to make sure the rail system is centered on your truck for proper seal fit on both sides. Review the below video for assistance.
To properly install your rails, follow the steps in your manual or watch the below video. Once tightened down, you will not have any gaps between the rails and your bed frame.
Do I have the right cover?
If the wrong size was ordered, please see exchange options & contact our support team: https://peragon.zendesk.com/hc/en-us/articles/360047937853-What-to-do-when-you-ordered-the-wrong-size-cover
While very rare, it is possible that a mistake was made and you were sent the wrong parts. See article here: https://peragon.zendesk.com/hc/en-us/articles/360047854073-Do-I-Have-the-Correct-Cover-for-my-Truck-