I got this Antigua Winds Alto Sax for a pretty good price (under $300) purchased for me to use while to filling in for a different alto player ( I usually play tenor/Soprano) in one of the Jazz ensembles I'm in. The person I bought the alto from didn't really explain anything about the sax. I started to distrust antigua saxes because I tried out several antigua Sopranos and Couldn't even pull a sound out of it due to a terrible mouthpiece and faulty parts. But, I decided to get an antigua alto and get a new mouthpiece for it after. I haven't tried it out yet because I haven't gotten a mouthpiece for it. I just can't tell if it what level of antigua it is, or what model. I am decided that it is either an A520LQ or an A521LQ (powerbell). Are there any major or suttle differences I could use to distinguish between the two? They are both student horns, right?