I believe they are satin nickel (coating over carbon steel). I had a CZ-85 combat with that finish. Held up pretty good, except for flaking around the slide rails which is apparently considered normal.
Tenda have two distinct ads, but it is not clear if one is for satin and one for black finish, or if one is for CZ-75 and one for CZ-75B with random finish, or if one is for CZ-75 satin and one for CZ-75B black because pictures and descriptions don't match, so the pictures may not be representative of each category they sell.