In principle it's easy as pie, just push down and twist. But as others have said it is difficult to install. You need to apply 100-150 pounds of downward force to compress the gasket. I put a towel over the hole and leaned on it with as much of my body weight as I could direct to it. With the other hand I twisted it, which got it partway turned. With weight applied I got it to turn the rest of the way by lightly tapping the back with a small hammer. Do use dishwashing soap on the gasket as other have suggested.

If you are small, you will probably need to get some help.

Perfect fit for my Kohler toilet. I installed 3 of them. (My wife used some of those drop in the tank cleaner things that destroyed the old ones). Installation wasn't bad. Rotate the old one to get it out. It doesn't matter which direction. Go with the easiest. Then to install the new one, put a little liquid soap on the plastic where the large seal will go. Install the large seal. REMOVE the flapper. This allows you to grip the unit with your thumbs and index finger knuckles as you push down hard and rotate it into place. Install the flapper and start flushing.

Please make sure to read the reviews about how to install this item. It does not come with ANY instructions and there is not much on the internet, other than the Amazon reviews that tell you how to install it. Many of the reviews talk about how difficult it is to install. However, if you follow the advice in the reviews it goes in very easily. That advice is: 1. put the grey gasket in a sandwich bag and then in the freezer for 30-60 minutes or so (I forgot and left it in for about an hour). 2. Remove the red flapper from the black valve. 3. After the grey gasket has been in the freezer for about an hour, coat both the top AND bottom of the gasket with vegetable/olive oil. 4. Put the gasket on the bottom of the valve. 5. Align the triangle tabs with the triangle hole and press down on the unit and turn until the back of the valve is parallel to the back of the toilet tank. 6. Install the red flapper; 7. Hook up the chain to the handle and, voila, you're done! It took about 5 minutes after I took the valve out of the freezer and it works great now (the toilet had been running every couple of hours because the old gasket leaked). I took off one star because the valve does not come with any instructions.

This was a perfect fit for my Kohler Santa Rosa 1.6gpf toilet. As other reviews have indicated, this part is an absolute beast to install. Like others, I recommend you put some sort of vegetable oil or other lubricant on the side of the gasket that faces the tank as well as on the plastic tines that will clamp to the underside of your tank. Hopefully this will last me another 10+ years!

Well made, perfect fit as a replacement part, but really should include instructions in deference to the DIYs, the likely customer for this kit. The foam seal needs to be heavily compressed for the flush valve to seat and twist into position and it is difficult to get the right leverage to apply enough force. I ended up placing the seal in the freezer for half an hour to compress it before installation, which made the job easy.