The Genuine Briggs BA21025 Flapper comes complete. Therefore it has the chain and hook to connect to the lever. Once the lever is pressed it causes the flapper to lift. Therefore it lets water flow into the bowl causing the flush. Also the ears that connect to the flush valve are plastic. Therefore they snap into place and will not rust. The chain and hook are metal. 

Also this flapper has the rubber seal on the bottom. Therefore it can prevent leaks into the bowl. The flapper site on top of the flush valve. Therefore if the flapper is bad it will allow water to leak into the bowl. The seal is rubber because it will stop leaks better than plastic. Also the cone of the flapper is plastic. However it fills with water to close. 

In conclusion, The Genuine Briggs BA21025 Flapper comes complete. It has the chain and hook to connect to the lever. Also the chain and hook are metal. Therefore they are more reliable. Also the rubber seal comes with this flapper. Which stops leaks from the tank into the bowl. This flapper is a genuine Briggs replacement part. It fits many Briggs tanks. 

• Genuine Briggs replacement part
• Plastic cone
• Complete with the hook and chain
• Rubber seal to prevent leaks
• Plastic ears