You mean the old original Serratus or after MEC took over? They were a low-key Canadian brand (Vancouver?) that died around 20 years ago. Their Genie 30l pack was a budget classic superalpine kit favourite.
I can't speak for the latest models but the originals were burlier than Osprey or modern Lowe Alpine and more like a light(er)weight Aguille Alpine type product. Def better than Mountain Warehouse. Seems to be more here from then: https://cascadeclimbers.com/forum/topic/28920-serratus-rip/