Sorry for the confusion.
Simply, I have vents (not vent covers) I'm installing (new, plastic) on the sides of my aluminum trailer approx 3.5" x 10". There's a flange with holes for screws around the perimeter of the vent, just like installing a new window in your home. However, I don't want to use screws, just epoxy or other adhesive to seal it and bond it, such as an adhesive chalk. I'm going to use what I have and not exchange it for an aluminum vent. I just need help selecting the proper chalk/adhesive/epoxy that will bond the plastic vent to the aluminum exterior wall of my trailer.Thank you