This is the only common snaffle bit that does not have any joint at all. With its slight curve, it is often considered to be a mild bit because it puts more pressure across the tongue instead of the more sensitive bars. However, for that reason it is not typically a bit that will aid in the lateral flexion of a horse’s head. Hence it is not often used in dressage, but more often as a pleasure riding bit on sensitive mouthed horses.
Because it lacks a joint, there is no possible nutcracker or pinching effect in the mouth, which also makes it milder and can be advantageous for horses with sensitive palates. These bits are frequently made from flexible materials, like rubber and plastic, which in combination with a curved shape, allows the pressure on the bit to be distributed more evenly in the mouth. There are also now differently shaped mouthpieces available, which perhaps make these bits more interesting or ergonomic for some horses.