We had ordered 2 of these bags a couple weeks ago from Safrax Chlorine Dioxide Clo2 tablets - high purity in contact with water. They are on back order and will take anywhere between 6-8 weeks to get here. I thought I posted about it, maybe in another link or maybe not. It’s only $30 for 500 tablets.I picked up 4 bags. There's 500 in a bag. So many uses.