Retail Store Supplies Poster and Card Suction Cups - We carry 3 types of suction cup holders Hook, Grip, and Plastic Tack. Clear vinyl suction cups allow you to use your storefront window for displaying sale signs and posters. They work well on showcases, cooler doors, mirrors, windows, and appliances. 12 suction cup holders per pack. Price breaks are at 5 and 10 packs.