Unicorn 14-A ideal for standard grow blocks.These bags are 2.2 mil in thickness and offer the same high-quality 1.5" x 1.5" 0.5 micron filter.These are great for standard growth blocks as your test new varieties, or you are just starting out.They are sized to fit 5-7 lbs of substrate.Yes, these Unicorn bags are still the original brand made in the USA to the high-quality standards Unicorn bags are known for.You can even save more time with MushroomMediaOnline’s own Fast Fruiting Mix that is the ideal mix of 50/50 hardwood sawdust substrate supplemented with 50% soy hulls.All of our Unicorn bags are Polypropylene which means they are autoclavable.