You will find many dentists advertising products such as Inman Aligner and Six Month Smiles. These are branded treatments (like Dyson or Hoover for vacuum cleaners), the treatment is similar in type and speed to other types of braces. Speed of movement is determined by biological processes in the patient, not the type of brace.
Removable Types eg Inman Aligner, LR, Barrer
Inman aligners and similar are removable braces with springs and acrylic pads on both sides of the teeth which are used to straighten the front teeth only. They are relatively bulky and we feel other braces can be better and less visible for front teeth.
Six Month Smiles
Six Month Smiles are a branded version of clear fixed braces stuck to and straightening just the front teeth. We do not use this brand but we can use InVu brackets in a similar way. This type of treatment can be good in certain situations but these need to be selected carefully.
With any type of brace teeth will be significantly straighter after 6 months. However to get the best results, and less chance of relapse, in most straightforward cases 9-12 months is a more realistic timeframe.