Gunze's Mr. Epoxy Putty Pro-L hardens quickly, is light, and is easy to sand. A strong ally of fans of modeling! The "L" in "Pro-L" means "light," as this putty is touted as being "super-light type." Perfect for modeling and remodeling your models. A two-part epoxy putty that you knead together to "activate." Hardens in one to three hours. The 38 gram package includes 19 grams of putty and 19 grams of catalyst.