What common feature do twisted bits have?

Twisted bits are designed to apply varying levels of pressure on the horse's mouth, which is why this aspect is critical in understanding their function. The twisting action allows the bit to create different sensations and pressures as the reins are pulled, enabling the rider to communicate more effectively with the horse. This can help in refining the aids and achieving a better connection between horse and rider. The variation in pressure can encourage the horse to respond differently based on the rider's signals, facilitating a more nuanced interaction.

In contrast to the correct answer, twisted bits are not always double-jointed, nor are they exclusively made of rubber or typically lacking any joints. The characteristics of twisted bits can vary greatly, but their primary feature is indeed the ability to apply varying levels of pressure to enhance communication with the horse.