Set includes 6 BPA free water valves ,6 glass weights ,6 stainless steel (87mm) wide flaps and shoulder straps, this set makes fermentation of sauerkraut very easy. Mason Jar Fermentation Kit is made of stainless steel material, will not rust, bend like tinplate material. The 3-piece airlock is made of BPA-free plastic. Add water to the airlock, which releases the gases produced by the fermentation while preventing oxygen from entering the jar to contaminate the fermentation, a silicone seal under the lid keeps items sealed, and grommets and seals keep new air out. The 3-piece airlock is removable and can be cleaned thoroughly with a small brush. The split design fermentation lid is easy to screw and assemble to keep your fermentation going strong. Excellent product, beautifully packaged, use it as a gift for you wife, she will definitely be very satisfied.