Hydro Flask Wide Mouth Flat Cap Bands With the new assortment of Wide Flat Cap Bands, your Hydro Flask can now be as unique as you Grab a band, add some color and flair to your Hydro Flask and let your true personality shine The Wide Flat Cap Bands fit on any Wide Mouth Flat Caps and can be used to add some color to your 18 oz Wide Mouth, 40 oz or 64 oz Hydro Flasks Separate yourself from the pack!