do I need this plastic container in my toilet tank?

I'm replacing my flush valve and the old one has this container attached to it, do I need it?
Here's a pic
http://img512.imageshack.us/img512/9905/flushvalvegy9.jpg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Looking at the picture, doesn't the container surround the outlet, rather than the flush valve? If so, it will not be especially easy to remove just because you're removing the valve. I think you'd have to remove the tank from the rest of the toilet.
Anyhow, if I understant the picture correctly, I think that might be there so that there is still water in the toilet tank when the flapper closes. This would cut down on how much water is used per flush.
So would a brick in the toilet, so I'm not sure the purpose of this container, which would have been much harder to install.
It has a dimple tube on either end. Is that to give access to the bolts that hold the tank on?
Wish I could see more. What's the differnece btween a website that lets you enlarge the posted picture and one that doesn't? Do they start with the same picture?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Joe wrote:

You don't NEED it, but it turns your standard (old standard) size tank into a tank that uses less water per flush. IOW, if you take it out, you are going to be using more water to flush your toilet.
--
Robert Allison
Rimshot, Inc.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.