I got this kit at Costco while it was on sale for $15. I was planning to replace the fill valve anyway and this kit contains a fill valve together with "water saving" dual flush contraption. After installing it and using it for a few days I found that this is a waste of time as this device does not save any water when used with 1.6GPF toilets.
This device has multiple design issues that would prevent it from working correctly in 1.6GPF toilet. Some of the issues would cause long term operational problems.
This device sits on top of a drain hole normally closed by the flapper. Due to this it raises the flush hole and minimum water level in the tank about 2 inches. This effectively reduces amount of water that can be used at the highest setting. If you watch animation on the MJSI website here, it shows that during full flush the water level drops to the bottom of the tank. This is wrong. The water level drops to the top of a blue cup covering the flush hole.
The "liquids" setting is controlled by the blue float. Manual instructs to allow about 2 inches of water above the blue float. This setting is impossible to achieve at least in my tank because the overflow tube top is about 1 inch higher than the lowest position of the blue float. So the low setting is impossible to to get to work in my tank.
The flush mechanism itself has many parts with relatively tight clearance. Although made of plastic, these parts are bound to accumulate the same deposits that are accumulated on a normal flapper and a fill valve. These deposits are likely to prevent this mechanism from operating correctly over a long term due to tight clearances between moving parts.
The flush is triggered by the steel wire moving in the sleeve, mechanism similar to a bicycle break. Although on a bicycle this mechanism is not submerged and has little contact with water, it is still recommended to lubricate it frequently. In the toilet tank this mechanism is unlikely to last any reasonable period of time without rusting and locking up. This in fact confirmed by multiple reviewers on Amazon.com.
It is stated on the box that no tools are required to install this contraption. If you watch installation videos on the manufacturers website, the first thing they do is list tools which you will need. This is NOT an install without tools.
The installation is pretty simple, although all pieces are large and somewhat of a tight fit in to my tank. After installation you need to adjust the device flow. The procedure to do this is not clearly described and some reviewers on Amazon describe it much better. Over all installation is simple but adjustment is not possible, at least with my tank.
The buttons are rather hard to press so if you have a small child it would be a problem. The "low" button does not release enough water even after setting it to maximum, so it is effectively useless. You can hold the button until you see the complete flush but this defeats the purpose of the device. The "high" button works OK, but the total volume of released water is less than with a regular flapper because of the device design. The 'high" flush is adequate even with reduced amount of water.
Not all is bad with this converter. Valve appears to be very quiet as the name implies. The flapper replacement does not leak water and closes securely at least while it is new. The "high" button works well as I already mentioned and it may even save you some water.
I think this device is a waste of time and money vs regular flapper when used with 1.6GPF toilet. The device is not likely to hold up as long as the simple flapper would, due to its complexity. The rubber gaskets are not replaceable and the company does not sell replacement parts. If the device breaks it is simple to replace but pricy comparing with a regular flapper. If this converter is to leak due to mechanical failure it will waste much more water than it will save. If you want to reduce water use it would be more effective to place few plastic bottles filled with water in to your tank to reduce amount of water used. To prevent leaks you can change flapper every few years. It is inexpensive and only takes a few minutes to replace. Valve included with the converter kit works well but similar valves are on the market fore less money.