UM Pro 20 features two proprietary, balanced-armature drivers, with a passive crossover. The dual balanced-armature driver design, delivers robust low end and crystal clear highs, with all the detail and nuance that musicians have come to expect from a professional in-ear monitor. The range, output, and power of the UM Pro 20 makes it an ideal choice for performing musicians and music lover looking for more low end in their mix. The Westone UM Pro 20 incorporates all the innovations and expertise that Westone has developed in almost 60 years of designing and manufacturing products for the human ear. The compact, low-profile, ergonomic design is comfortable, and can be worn for hours and hours. . Westone’s proprietary silicone and comfort foam eartips are provided in 5 different sizes and enhance the performance of our In-Ear Musicians’ Monitors by ensuring a superb fit and by provide superior noise isolation. Ambient sound levels are reduced an average of 25 dB, which makes UM Pro 20 ideal for use onstage or in other noisy environments.