This is advertised as a medium impact bra.  It def does the job for aerobics and weight training.  It is compressive, but not uncomfortably so.  I haven't had issues with the zipper coming undone, if it is flipped all the way down, it's locked into place.  It totally gives the uniboob look, so it's not a fashion statement.

I bought a popular specialty store's sports nursing bra and was disappointed with how the thin straps cut into my trapezius.  I am a D-DD depending on feeding state and just pulling out or under a regular sports bra is really awkward.  So I like the zipper access for nursing.  I also think that it will be good post nursing, given moving comforts quality of other items, I expect this to last several years.