Genuine Husqvarna Retaining Ring Part #: 503 27 21-01 Fits Husqvarna: 362, 362 XP, 362 XP EPA, 362 XP SPECIAL, 362 XP SPECIAL EPA, 365, 365 SPECIAL, 365 EPA, 365 SPECIAL EPA, 365 H, 365 X-TORQ, 365SP, 371 XP, 371 XP EPA, 372 XP, 372 XP EPA, 372 XP X-TORQ, 385, 385 XP, 385 EPA, 385 XP EPA, 390, 390 EPA, 390XP, 565, 570, 570 II (Valid only for 967 10 83 -XX), 570 EPA, 572 XP/XPG, 575 XP, 575 XP EPA, 576 XP AUTO TUNE, 576 XP Jonsered: 2063, 2065, 2071, 2071 W, 2077, 2083, 2083 II, 2163, CS2163, 2165, CS2165, CS2165 EPA, CS2166, 2171, CS2171, CS2172, CS2186, CS2188, CS2188 EPA