Reusable grain jar lids for wide-mouth mason jars. Each lid comes fully assembled: PP5 polypropylene body, 20mm PTFE filter sticker (0.3 micron), self-healing silicone injection port, and a silicone o-ring seal. Screw it on, sterilize, inoculate.

What you get

• 4 fully assembled lids

• Fits wide-mouth Ball, Kerr, and equivalent mason jars (jars not included)

Why these work

• Silicone o-ring seal. Seals against the jar rim instead of relying on metal-on-glass contact, so the seal holds through sterilization and storage.

• PP5 body, rated to 330°F. Sterilize it as many times as you want. I've been running the same lids for years, and they'll likely outlast your interest in mushrooms.

• 0.3 micron PTFE filter. Hydrophobic, so it sheds condensation instead of wetting out. It's the same filter sticker I sell by the sheet, so swapping one takes seconds.

• Self-healing injection port. Closes behind the needle after each inoculation. With normal use it goes several months before it needs attention. Heavy, repeated sticking wears it out sooner.

• Fully autoclavable. Lid, filter, port, and o-ring all go through the pressure cooker or autoclave.

Good for

• Grain spawn and master spawn jars

• Anyone done drilling and gluing their own lids

A small, inexpensive add-on. Most people grab a pack alongside grain, agar, or a sheet of replacement filters.