Swimline 4x4 Feet Winterizing Air Pillow for Above-Ground Pool Cover, 2-Pack

how do i inflate this pillow ? I see a big red plug but no hole. Do not want to mess around and rip the pillow,

Do these pillows have a place to tie them to each other in the corners?

How do you blow these up??

How many pillows do i nee for intex 21' above ground pool?