I bought a lime green replacement band for my Fitbit Blaze from I-Smile on Amazon and I will compare it to the original Fitbit band that came with my tracker. The replacement band is the exact same size (length and width) as the original and just like the original it has the size listed on the inside of each side of the band. When I attached the replacement band to the frame it was just as easy as the original and the fitment was perfect. The pins used to attach it were easy to slide and they did not bind. The only difference I noted between the two is the silicone, the original band is slightly and I do mean very slightly more pliable. With that being said the replacement band is very pliable and it is just as comfortable while sleeping as the original.
I purchased this product at a discounted rate.