Edit: i am confused. Some ppl say that the Westmark is midwide others say the Blacklist is midwide.
I just checked Arbor's site the Blacklist is definitely the midwide version, 157 has a waist spec of 260mm.
I own the arbor westmark and it is definitely the blacklist that is midwide. Ive seen the blacklist in person and have compared it to my board. The width is much bigger on the blacklist.