This tek is outdated in a few ways:
1) Coffee filters are worthless as filters. Ignore this part.
2) Tyvek and other filters will be useless when wet. Be sure to just use tyvek in the order: jar, round jar lid with poked holes, tyvek, lid ring. Use small holes, and your tyvek will remain dry
3) Cover each jar in aluminum foil before pressure cooking. As above, wet tyvek = bad. Aluminum foil will keep your pressure cooker from dripping onto it
4) Do not use a spoon to mix your spawn into your bulk substrate. Please review RogerRabbit's videos on Youtube, or order the full set for only $40.
5) Do not let your jars touch the PC as it is shown, and do not load them sideways. Water will splash onto the tyvek or the jar will touch the side, exposing it to disproportionate heat and cracking it.
Edit: The little square things are inoculation rings made of self-healing RTV silicone. Funny since the only one it's on is the one receiving the G2G transfer :/
What are those little square things on the lids in the bottom picture?