If you’re striving to reduce your carbon footprint, forget those boxes of plastic bags. An alternative for packing school and work lunches or snacks is the new Stasher reusable sandwich-size bag from Bay Area company Modern-twist, known for innovative sustainable products. Made from platinum silicone, the bags ($11.99 each) have a pinch-press seal that closes airtight. They are safe for the microwave and freezer and can even be used to boil frozen vegetables. Clean them in the dishwasher. Stasher bags are transparent and come in aqua, clear, and citrus, as well as circus, space animal, and monster prints. They may seem pricey, but you’ll be making a wise investment: They last three years. And you’ll feel good about doing your part to help the environment. Available at Kitchenwitch, 671 Centre St., Jamaica Plain, 617-524-6800; Didriks, 190 Concord Ave., Cambridge, 617-354-5700 and 2284 Washington St., Newton Lower Falls, 617-467-4847; Tags Hardware, 29 White St., Cambridge, 617-868-7711; Wayside Gourmet, 80 Andrew Ave., Wayland, 508-358-2123; or go to www.stasherbag.com