Vintage 1930s Clark Brothers Chewing Gum Co. Retailer Incentive Coupons

Here are two, original, old retailer coupons from Clark Brothers Chewing Gum Co. of Pittsburgh, PA. These were redeemable to store owners who sold Clark's Chewing Gum by saving and sending in 10 of them for a free box of product. Those who sent in 50 certificates at one time would receive 6 free boxes of gum. This was a way of incentivizing sales and increasing store owner's profits. These coupons are in very good shape with light age or wear. One has an expiration date of January 1, 1935 and July 1, 1940. Scarce chewing gum collectibles!