nylonImportedPro Waterproof and Sweatproof : when you're training and dripping with sweat, it will be as effective as ever to resist interference and keep the original good signal sent to the sensor for accurate heart rate values.Work With: This replacement chest strap fits for mz switch (Not Compatible for MYZONE MZ-3 and Not Compatible for MZ-1)Adjustable size between M:24.8~36.6" inch /63~93 cm. The Wearable size is larger than the adjustable size,streching more than 1.2timesCOMFORTABLE and GREAT WORK: With the chest strap based on Nylon and Spandex material, it can be attached to your skin closely. Soft fabrics and adaptive electrodes make it extremely sensitive to your heart's electrical signals.EASY USE and CLEAN: Utilizing the same snap attachment method;The sensor transmitter should be removed before clean,the soft strap hand-washed after used,dry it naturally.Name and Date Tag When participating in group activities or competitions, it is easy to identify and find your own heart rate band without making mistakes. Of course, you can also simply record dates and results, etc.NOTE: Only Belt Strap, Please check your heart rate monitor model and wearing size before ordering. The heart rate monitor chest strap is an enhanced version of waterproof and sweat-proof,and when you're training and dripping with sweat, it also effectively and accurately detects your real-time heart rate signal to your transmitter. it's an adjustable elastic replacement strap fits for MYZONE switch ; 1. Specifications: A).Belt length: Medium; B).Material: Nylon + Spandex. C).Color:Red 2. Features: Soft elastic strap provides a comfortable fit. Easy to use, clean, durable, highly efficient and stable. Soft fabrics and adaptive electrodes make it extremely sensitive to your heart's electrical signals. 3. Instruction： 1).Wet the sensors on the inside of the strap. 2).Attach your heart rate monitor transmitter to the strap. 3).Attach the strap around your chest. 4).Make sure the monitor sits above the base of your chest bone. 5).Package Included: 1 x Chest Belt Strap (only strap not including transmitter)