The Stihl 3/8 7-tooth annular chain sprocket assembly (code 1122-007-1001) is an original spare part for Stihl 064, 064 R, 066, 066 M, MS 640, MS 650, MS 660, MS 661, MS 661 C-M chainsaws. Includes 8-tooth annular spool ring, seeger and disc diam. 27 mm MN