BansusuGalaxy-Print School Rolling Trolley Backpack for Elementary Boys Bookbag on Wheels

What type of screws are used for this backpack?

Can i just buy the backpack as a replacement? I already have the wheel base.

Is there a cover for the wheels?

El bulto es muy linda el tamaño perfecto ,lo univo que vino un poco un dido en el carrito y se desliso por el lado me he tratado de comunicar con ello