Mic, it’s clear polycarbonate stuff - ideal for sous vide cooking. Not essential, but I had nothing at all, not even an old cooler to cut a circular hole in, so decided to get all set up at once. There are four sizes, from what I see on Amazon.
LIPAVI Sous Vide Container - Model C15 - 18 Quarts - 17.6 x 11.4 Inch - Strong & Clear See-through Polycarbonate - Matching L15 Rack and Tailored Lids for virtually every circulator sold separately.
The lid can be ordered to precisely fit most sous vide heaters. Not cheap - the three components totaled $116 US. The rack, which is even more non-essential, is $60 alone.
However, it’s good stainless steel and they make a substantial case for its efficacy at doing larger batches of things, i.e. keeping the bags from touching each other, keeping an even flow of water around them all.
So, a total of $215 with the Anova cooker. Two or three times of my wife and I eating in, versus going out, should more than equal such, and I’m sure we’ll cut down the restaurant visits by far more than that.