Quiet Glide Outside Curved Track, Use With 20in Wide Ladder, Black Assembly includes: (1) LL.B+S-20.08 (WIDE cross brace sub assembly) (2) LL.UGUIDE.08 (upper inside guide) (4) 16.BB1420035.08 (KD bolt, 35mm long) (4) LL.ACORNNUT.08 (acorn nut, 1/4-20) (4) 0.OPC10134.08 (oval-head #10 x 1-3/4" screw) (4) LL.FLT10034.08 (flat-head #10 x 3/4" screw)