Structural component of intermediate filaments in the hair shaft (PubMed:15744029, PubMed:25557232). Forms obligate heterodimers with type I hair keratins, which assemble into keratin intermediate filaments that contribute to the structural integrity and mechanical strength of the hair shaft (PubMed:15744029, PubMed:25557232). . This is the function of KRT86 (keratin 86, ENSG00000170442).