The dress and accessory rental company, Rent The Runaway, ran a promotional campaign in which they give their customers a free accessory with an online order.
The gift they give away can be made of virtually any material, so this campaign can be run with a tight budget, or a higher-end product can be provided with larger budgets. The fact that jewellery and accessories already have a high perceived value with ensure that customers feel valued, making it more likely they'll purchase in the future or recommend your brand.
It's primarily an incentive product, incentive to not only get customers to spread awareness of the brand, but also incentive to get customers purchasing.
The way in which the campaign has been run, through the use of social media, will also help to drive traffic to their website, as that's the platform customers will have to use to take advantage of the promotion.
Accessories and jewelry are more than often worn in public. This means high viability for your brand, especially if the gift is branded well.