Oregon 55-406-0 Jet Fit Express String Trimmer Attachment Head Oregon 55-406-0 Replacement Jet Fit Express Trimmer Head Adaptors, bolts and nuts included to fit most trimmers. The Oregon Jet-Fit express features square eyelets for use with Flex Blade. Easy loading and unloading. Just push and pull Square eyelets hold Flexi Blade securely, and at the right angle for maximum cutting force Can be used with all sizes and shapes of line Replaces Oregon 55-401-0