This is the old style threaded sensor for use with separate T connection. It is used, but less than 1 year old. I purchased July 25, 2010. I got 1 more year's use of my SWG, but now the cell has reached end of life. I decided to replace everything. So, if you have the older style and are getting error codes 172 or 181, you may have a faulty sensor. $75 shipped, which is less than 1/2 of what you would pay for a new one.
http://www.discountpoolmart.com/product ... ts_id=2751 - link to flow sensor