Intradermal

Intradermal injection is the injection of a substance into the dermis, just below the epidermis. This route has the longest absorption time as compared to subcutaneous injections and intramuscular injections. As a result, it is used for sensitivity tests, like Tuberculin and allergy tests, and for local anesthesia. Additionally, the body's reaction to substances is more easily visible since it is closer to the surface.

Common injection sites include the inner surface of the forearm and the upper back, under the scapula.

Equipment include syringes calibrated in tenths and hundredths of a milliliter. The dosage given is usually less than 0.5 mL, less than given subcutaneously or intramuscularly. A 1/4" to 1/2" long and 26 or 27 gauge thick needle is used.

The angle of administration is 5 to 15 degrees, almost against the skin. With bevel (opening) side up, insert about 1/8" with entire bevel inside and inject while watching for a small wheal or blister to appear.

...
Wikipedia