The phrase "are of medium length" is correct and usable in written English.
You can use it when describing items that are not extremely long or short. For example, "The sleeves of the shirt are of medium length."
The tail is of medium length, except in males of those species with ornamental tail features.
The first planing operation was done with the roughing, or fore, plane, which was of medium length, possibly 16 18 inches.
The wings are shorter than those of most other procellariiforms and are rounded at the tips; the bill is of medium length; the nostril tubes (common to all members of the order) are united on the upper surface of the bill; the toes are webbed, except for the hind toe, which is small and elevated; the tail is medium to long and square, forked, or wedge shaped.
Moreover, in order for the design to be complete, both QD-SOAs must be of medium length, provide a maximum modal gain such that their net gain exceeds by two orders of magnitude that at transparency, be biased at moderate current density and exhibit an electron relaxation time from the excited state to the ground state as fast as possible.
The muzzle should be of medium length and should not be too tapered.
The neck is of medium length and strong, often slightly arched.
The neck is of medium length, the withers are pronounced, the shoulders sloping and the chest deep.
The neck is of medium length in the modern Mérens, and often shorter and broader in the traditional version.
If your hair curls easily and is of medium length (only extending about two or three inches past the pony-tail band), you may need only a few bobby pins since the curls will stay in place on their own.
Although plant oils tend to be largely unsaturated, there are notable exceptions, such as coconut fat, which is highly saturated but nevertheless semiliquid at room temperature because its fatty acids are of medium chain length (8 to 14 carbons long).
