Hero Arts-Clear Stamps. These clear stamps peel off their backing and stick to any acrylic block making for easy stamping. Simply apply your favorite ink and stamp crisp clear images! They are made from 100% photo-polymer which is latex free, phthalate free, non- toxic and biodegradable. Available in a variety of designs (each sold separately). This package contains Invitation Themes: a set of twenty-one clear stamps on one 6x4 inch backing sheet. Non-toxic. Latex and phthalate free. Made in USA.