Multi-Purpose Water Snake - Water Barrier, Dehumidifier, and Draft Stopper - Large by Bandwagon

What is the dusty residue that is pouring out of the snake? It's not sand, so what is it? I hope no chemicals! is it safe around children and pets ?

This seems to have a different seller. So what are the dimensions of the regular and large size snakes?

Will water pass through it to other side once its completely saturated with water?

can you waash it