Bobbin Notes: All bobbins are composed of 6/6 Nylon material except PB305, PB305A and any bobbin with the suffix "/VO". The PB305 and PB305A are composed of 6/6 Nylon Glass Filled. The "/VO" indicates a material that is rated for UL 94 VO flame class. Micrometals also offers bobbins for the following metric and custom E-core sizes for sample and small quantity orders; E80, E99. Their part numbers are, respectively, PB80, and PB99.