Compatible Models - Compatible with Fitbit Charge 3 / Charge 3 SE / Charge 4 (You will get two bands for your Fitbit charge 3/4 , one is the classic model,one is the sports model, they can be used interchangeably. The Fitbit tracker is not included.) Premium Material - replacement band is made of high-quality liquid silicone material, its soft, comfortable, lightweight, durable, sweat-proof and waterproof. Its very suitable for sports, fitness, swimming, yoga, outdoor and other scenes. Seamless Match -Fits well with no gap. Simple to install and remove, No tool required. The end of the band has a lug, which fit your charge 3/4 smart watch in place and locked precisely & securely.We added an extra loop,our notch is also designed little longer to make it attached super tight,not easy to loose and fall off. Two Adjustable Size - Small size is for 5.5" - 7.5"(140-190mm) wrist, Large size is for 7.1" -9.1" (180-230mm)wrist. Stainless steel metal buckle,you can easily adjust it to fit your wrist. Our Service - We insist on ensuring high quality standards to customers, if it still has quality issue, please feel free to , we will solve the problem as soon as possible until you are satisfied.