Whitmor's new valve design has no cap. Other bags rely upon a cap to be tightly sealed to keep air out but air can still seep through the cap causing the bag to deflate overtime. Whitmor's new technology in our no-cap valve created an airtight harrier keeping items condensed for the long haul. If you do not have a vacuum handy you can compress bags by simply hand-rolling the bag to remove excess air. Increase storage space in your suitcase, luggage or closet. Whitmor is a 4th generation family-owned and operated business. Since 1946, Whitmor has been dedicated to bringing organization home by creating products that simplify everyday life. Ensuring that those products are built with integrity, value, and innovation is our commitment to you. And our promise is that we will always be here for you should you ever need us as we stand behind our product 100%.   Whitmor customer service is available in English and Spanish Monday through Friday from 8 am - 4:30 pm CST.  Call us and we will gladly assist you in your language.  You may contact Whitmor toll-free at 1-888-944-8667 or via email at help@whitmor.com