. Hydro Flask - Standard Mouth Flex Straw Cap. Color Black. Low Stock. On sale for $11.21. MSRP $14.95.. 4.5 out of 5 starsBest SellerAdd to favorites. 0 people have favorited this9 left in stockBrand NameHydro FlaskProduct NameStandard Mouth Flex Straw CapColorBlackPrice$11.21MSRP: $14.95Rating4Rated 4 stars out of 5(210)