In changing the pick up system for the turtle tanks, I had add many more strainers and bends in the pipe for corners.
So I got a bag full, when I find I need to use extra, no problem, I do not have to run back out to the store.
My pet turtle got so fat the turtle dock sunk under her weight.
So I had to build a platform that is water proof and could hold the weight of the turtle with out being easy for the turtle to destroy since they like to investigate what ever you put in their tanks.
in the picture below you can see how I used these and why I needed to buy them by the bag full.