The coil consists of an internal wire and and external spring.
Wire rope made out of steel is used through the centre of the coil for added strength and stability. It is made up of lots of thin wires, wound together to form a strong, yet flexible rope.
The external spring can sometimes be doubled up for even more strength. The spring shape allows for movement of the cable and the high carbon steel is used because of its ductility and strength. The coil is heat treated to further improve its properties, making it ideal for manoeuvring pipes and breaking down blockages.
As with most things, the quality of the product is reflected in the price. A less expensive drain auger may not have undergone the same standard heat treatment as a more expensive version. The cheaper tools are also less likely to include the double spring and sometimes even the wire rope is missing.
Although these features improve the quality of drain augers by preventing rusting, kinking and knots, it does not mean that those without will be completely inadequate tools. You can judge your needs by the frequency the tool will be required and the severity and location of the blockage (external drains will be more tricky to manoeuvre for example). Some cheap models will tangle and get stuck when faced with a large hair clog, so remember to weigh up the costs against the advantages.
The closet auger extra features include die cast handles, a brass-coated steel tube and a vinyl bowl guard.
The drum is is moulded from a high impact plastic. This means it is hard and able to withstand being knocked about.