Hydro Flask Stainless Steel Flat Cap - Standard Mouth

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The Stainless Steel Flat Cap is perfect for those who prefer their liquids never touch any plastic. The top is made from polypropylene PP#5, while the inner threading is made from 18/8 stainless steel, which ensures an all stainless steel contact with the flask's contents. 

The Flat Cap fits on our Standard Mouth flasks, including the 12 oz and 21 oz flasks.

Like all Hydro Flask products, the Stainless Steel Flat Cap is both BPA and toxin free.

Posted by upant on 07/21/2014

1 Star Rating

Misleading web info and bad customer service

I ordered stainless steel cap from web site where information was misleading. They didn't fit in my bottles. Contacted customer service for return and they are not ready to provide return shipping even if I explained the issue on website. It is better to throw the caps rather than spending more money on shipping. I own several bottles from Klean Kanteen and Hydro Flash. I have bought many products from Klean Kanteen and return without any issue. Now time to ditch Hydro Flask bottle and stick with Klean Kanteen.

Posted by Sha One on 07/16/2014

5 Star Rating

Wanting a 40 oz stainless wide mouth

I have this for my standard wide mouth and I love it. Ice seems to stay frozen longer with the stainless. I REALLY want a wide mouth version as well. Make it happen Hydro Flask! Great product.

Posted by Shelly Rodrigues on 06/21/2014

3 Star Rating

Good lid but not leak proof

I used this lid when I had some pepsi in the bottle and the the lid wasn't leak proof. The pepsi came up and out slowly when the bottle was turned on its sideā€¦is it cause of the carbonation, maybe but I'm not sure.

Posted by Kim Keeling on 01/16/2014

5 Star Rating

Thank you Hydro Flask!!!!

I recently developed an allergy to plastic, especially water bottles. I'm so thankful for this lid!!!! Hydro Flask has made my life so much easier! Thank You!!!

Posted by SunTrish on 09/24/2013

5 Star Rating

Love Hydro Flask

Like everything Hydro Flask, we love these products. I especially like that there is an option for a metal - not plastic - top, and we always use this one when we have a hot beverage in our Hydro Flask. The metal lid doesn't seem to drip as much steam when removed from a hot beverage as the plastic lids do. I wish this top had a ring for ease of carrying. I sometimes use Kleen Kanteen's metal and bamboo top with folding ring as it seems to fit the standard mouth Hydro Flask, but I am not as confident about it not leaking with the KK lid if the bottle is going to be tossed around.

Posted by Mike D on 09/24/2013

5 Star Rating

Good Lid

There is not much to say. This lid keeps the liquid in. Keeps the liquid cold. It works as advertised.

Posted by Hawaiian style on 06/20/2013

4 Star Rating

Why for the standard mouth but not for the wide mouth?

Really would like to buy this for my bottles but I only own the wide mouth bottles. Also just like another person wrote in the hydro flip review it would be nice to have some kind of strap from the bottle to the cap. So you don't drop the nice stainless cap on the ground and damage or loose it. Also it's nice to have some way to strap it to your bag or waist when on the move. Mahalo:)