Probably 1.5 mil. I did vac seal a buncho ammo before it tragically fell in the lake in a freak canoe accident.
Used to vac-seal hops and malted barley/ grain. Also beef, chicken, pork, lamb... went through an amateur butcher phase. T-bones and pork chop bones would regularly rip through. Plus the seal would frequently fail. The Weston had like double the sealing surface at the time. The foodsavers are great for low volume home use. I was just trying to use them beyond their reasonable intended use.
Looking at Weston's website it seems they sell their own brand of bags and rolls now, but still 3mil.