Using promotional products to encourage repeat business

Here are interesting findings on a report when promotional products were used to encourage repeat business:  

Customers who receive promotional products, on average, return sooner and more frequently, and spend more money than customers who receive coupons. In two separate studies, SMU researchers tested whether promotional products would outperform coupons in the area of repeat business and sales.

FINDINGS - Food Delivery Service
• Customers who received promotional products reordered up to 18% sooner than those who received coupons and up to 13% sooner than those who received no promotion.
• Customers who received promotional products also averaged up to 18% more orders than those receiving coupons and up to 13% more than those who 
received nothing.
• In summary, customers who received promotional products reordered more quickly and ordered more often than those who received no promotional 
products.