Online retailers, such as Zalando or AboutYou, are confronted with product returns of up to 60%. From a retailer's perspective, product returns are a double-edged sword. On the one hand, generous regulations can reduce customer uncertainty when buying online and increase the likelihood of purchase and customer satisfaction. On the other hand, product returns cause considerable costs for retailers and the environment, e.g. for shipping, packaging, preparation, etc. Due to the importance of product returns, online retailers are continuously looking for suitable tools to reduce the number of product returns without compromising the customer relationship. As part of our research, we analyse the effectiveness of different instruments for reducing returns in order to provide concrete design tips for online retailers.