Looking for Tonneau Cover Recommendations

[Chicagowin]

Noob question

I ordered a bakflip f1 and after watching some videos it looks like you gotta drill a hole in the bed for z as drainage tube. There are plastic plugs in the lower part of the back of the bed bid that what people are drilling into?

 

[Niners55]

I ordered a RetraxPRO XR through Rick here on the forums, and he was awesome to deal with. He worked super quickly and had the best price. UPS on the other hand...2 part package was supposed to get here yesterday, and I got one out of the two with tracking not showing where the other package is or possibly could be . Good thing I'm good at waiting, I guess.