Type 4 hair can range from fine and thin to wiry and coarse with lots and lots of strands densely packed together. Coily hair has fewer cuticle layers than any other hair type, which means that it has less protection from the damage inflicted by combing, brushing, curling, blow-drying and straightening.
Type 4a is tightly coiled hair that has an "S" pattern. It has more moisture than 4b; it has a definite curl pattern. The circumference of the spirals is close to that of a crochet needle. The hair can be wiry or fine-textured. It is very fragile with lots of strands densely packed together. Type 4 hair has fewer cuticle layers than other hair types, which means it has less natural protection from damage.
Type 4b has a "Z" pattern, less of a defined curl pattern. Instead of curling or coiling, the hair bends in sharp angles like the letter "Z". Type 4 hair has a cotton-like feel. The hair is very wiry, very tightly coiled or bent and very, very fragile; you must take great care when working with it. Type 4 hair can range from fine/thin to wiry/coarse with lots and lots of strands densely packed together. Type 4b hair often shrinks up to 75% of the actual hair length.
Type 4c hair is composed of curl patterns that will almost never clump without doing a specific hair style. It can range from fine/thin/super soft to wiry/coarse with lots of densely packed strands. 4c hair has been described as a more "challenging" version of 4b hair. Some say 4c looks identical to 4b except that the curls are so tightly kinked, there is seemingly no definition. 4c hair can shrink more than 75%.