Longscale Steelstrings for Dropped Tunings
If you play a lot with dropped open tunings on an acoustic guitar which was built for playing in standard (concert) tuning you can have the problem of the tension on the dropped strings being so low that they flap about with the resulting loss of tone and, possibly, bad intonation as you go up the neck. Physics dictates that the longer the scale length the higher the string tension required to reach a certain pitch so lengthening the scale tightens the strings. My longscale guitars have a scale of 690mm (27.2") compared to around 650mm (25.5") for a standard steel string and the extra tension this creates means that even when the tuning is dropped the lower strings still have sufficient stiffness to sound strongly and not flap and buzz. In addition the saddle has the intonation set for dropped tuning and so there is much more accuracy of tuning as notes progress up the neck. The longscale can be specified for any of my acoustic guitar models.

Effectively the bridge is pushed a little further back into the body and the nut moves a little further away from the body - neither has much effect on the way the guitar plays and after a few minutes you do not notice that you are playing a different scale. But you will notice a difference in sound. and playability.