This is a Tyvek filter for mycelium bottles. It is a set of 50 sheets, 150mm x 150mm. As shown in the image, it can be used by sandwiching it between 1400cc poly bottles or glass bottles. Of course, it can also be used with 800cc bottles. It has good breathability, does not tear even when wet, prevents the entry of harmful bacteria and insects, has good moisture retention, and can be washed and reused. This product is used by many mushroom bed manufacturers. You can buy it immediately. Negotiations for discounts on this product are not accepted. We will not respond to comments regarding discounts, so please understand. If you would like a quantity other than the quantity being sold, please let us know. This is a safe and secure anonymous delivery service where the buyer does not have to disclose their name or address. We cannot accept requests for date and time of arrival. Basically, if payment is confirmed in the morning on weekdays, we will ship the same day. Please note that we cannot ship on Sundays and holidays. If you have any problems upon arrival, please contact us via message. We also sell a set of 100 sheets. Japanese Giant Stag Beetle Japanese Giant Stag Japanese rhinoceros beetle Rhinoceros beetle Stag beetle Stag Insect jelly Pro jelly Mycelium bottle Mycelium bottle