M10 x 2 ½” Carriage Bolts (#88), two Ø ¾” Washers (#107), and two M10 Aircraft Nuts (#110).
B.) Attach the Butterfly Stopper (#31) to Butterfly Base. Secure it with two M6 x 3/8” Allen Bolts (#58).
C.) Attach the Backrest Board (#39) to Middle Vertical Frame. Secure it with two M8 x 2 3/8” Allen Bolts (#103) and two Ø 5/8” Washers (#106).
DIAGRAM 4
13
STEP 5 (See Diagram 5)
A.) Insert the pivot on the Right Butterfly (#13) into the hole on the Butterfly Base from bottom. Secure it with one Lock Ring (#35), one Ø ¾” Washer (#107), and one M10 x 5/8” Allen Bolt