Easy to install: You need to put the spool in the right direction and close the cap to fix it. The reels work well once you get it right. Auto Feed: It feeds automatically when needed, which is achieved by centrifugal force, so please note that the auto feed should be in high speed Pre-loaded spools: Manual winding usually causes uneven surface, it makes the trimmer difficult to work, pre-installed spool is more convenient, protects your Ryobi cordless trimmers and extends the lifespan of your machine. ryobi trimmer wire spool works with the following string trimmer models: 18V -OLT1825, OLT1825M, OLT1830H, OLT1831, OLT1831H, OLT1831S, OLT1832 P2000, P2001, P2002, P2003, P2004, P2005, P2006,P2200 RLT1825, RLT1825Li, RLT1825LL13, RLT1825M13, RLT1830H13 RLT1830H15, 25, RLT1830Li , RLT183113, RLT183115 RLT183125, RLT1831H20, RLT1831H25, RLT1831H25 RLT1831H25PK, RLT183213, RLT183220, RLT183225RLT183225PK, 24V - RY24000, RY24020, RY24021 , RY24200 40v - RY40001, RY40021, RY40200, RY40201, RY40210, RY40210A