The advancement of technology has brought forth a variety of wearable devices that promise to monitor signals effectively. In this research, we propose to compare different types of these devices available on the global market, categorizing them as smartwatches, smartbands, smart rings, signal monitors, and smart straps. The focus is on analyzing the types of biological data that these devices are capable of evaluating, as well as the different ways of accessing this data that they offer to users. Furthermore, we examine the certifications associated with these devices, considering their importance in warranty for the accuracy and reliability of the data collected. By offering a comprehensive analysis of these aspects, this research provides in-depth insight for consumers, healthcare professionals, and specific researchers in the selection and proper use of these devices for monitoring specific signs.