The product is authentic, therefore it is functional based on specifications, etc. The only hesitation I express is that although my manual stated that I could use this length/size of spool-trimmer line, it ultimately does not fit the GL301 and I am not absolutely sure if it is the machine's fault or the specific spool (because it does not seem to have the notches that the machine's original spool has). It may be necessary to purchase the entire cassette with the notches for it to work. That's why I am giving one star..