Flange Accessories Dn 40 (1 1/2" Pipe Size) Required Accesories Per Connection: Four Pn:135-940 M16X55 Bolt Kits One Pn:100-164 Dn 40 Seal When A Control Is Used Alone, One Mating Flange Is Needed For Each End, For A Total Of Two Flanges. When One Control Is Bolted To Another, Such As An Frs To A Dmv, One Mating Flange Is Needed For Each End, For A Total Of Two Flanges.