A medium radius L/H turnout is a compromise between a space saving small radius low speed turnout and a high speed large radius L/H turnout.
Most model railway layouts have limitations on their size and hence the maximum radius available for curves and pointwork.
4-6-0 coupled locos are unlikely to traverse a small radius turnout, in full size prototypes would use a large radius turnouts for passenger traffic, so, in our model railways, medium radius turnouts offer a compromise.
There are two left hand variations - Electrofrog for smooth running and Insulfrog for easy installation.