I consider this a good example of a successful UX/UI design because of its ease of use and simple yet efficient design. Its use is fairly self-explanatory, if not self-evident. Assuming the material used is silicone, it makes for a flexible and heat resistant device that is very portable and versatile when it comes to fitting different cup and mug shapes. It also makes for an easy clean-up. The ribbed sides of the reusable filter holder help it from slipping down the sides of the mug, which is important to avoid having the entire thing (especially the unwanted coffee grounds) fall into the contents of the mug. The funnel shape allows for a centralized concentration of coffee grounds, which creates a steadier stream and a better cup of coffee. Overall, I think this design fulfills its requirements in a way which focuses on ease of use and appealing functions.