Good replacement for my Model 660 Waterpik
Good replacement for my Waterpik Model 660.  Easy to install.  The shape is slightly different than the original so it doesn't fit perfectly in the holder but it stays in place just fine.  The handle holds the tip perfectly.  As others have noted, there appears to be a slight decrease in pressure but in my opinion not enough to prevent effective water flossing.  Given the price and free 2 day shipping, I think that it is still worth 4.5 stars.  I haven't had it long enough to comment on durability.
Rating: 5 stars