The standard low profile insert gives a near flush finish in sheet materials without the need to countersink the hole. To increase torque to turn values, especially in softer materials, splined inserts may be used.  Where a high push out load is applied such as on a screw in foot large flange inserts will be the most suitable.

Hex inserts can be used where corrosion of the insert or mating bolt could result in the threads binding and making the insert turn if the bolt head is forced. A typical example would be on the underside of a car for instance. Closed end rivet nuts can ensure that screw drivers or other tools cannot be poked into electrical items and cause damage. Whilst their use will obviously help to resist fluids from passing through the thread these inserts do not create  a water tight joint unless additional sealing materials are used.