Potting Mix Bar || Pumice
Price is per (mounded) scoop.
Pumice is made from volcanic rock. Similar in function to perlite, pumice provides drainage in your potting mix. Many houseplant enthusiasts prefer pumice to perlite because it is mined in a more eco-friendly manner than perlite and it is heavier, so less likely to float to the top of a potting mix.
Third photo shows typical amount of a mounded scoop.