Joe Coughlanwrote a review of Klean Kanteen Loop Cap on August 23, 2017
I lost the cap to my Klean Kanteen months ago after a move and finally purchased this cap after not using my bottle for awhile. It's not hollow like my old one (design update maybe?) but I never notice the difference. It fits just right, as you'd expect, and now I can use my Kanteen again.