Ziploc brand Slider Freezer Storage bags have an expandable bottom that opens into a flat base, helping the storage bag stay upright so itÕs easy to fill up. The Smart Zip Seal lets you hear and feel the bag close so you can feel confident that your food is protected. Ideal for packing heavy items, keeping leftovers fresh, and creating healthy recipes with ease. You can also use them to store everything from cosmetics to business cards and keep your office, desk, or classroom organized.