The Blu 18 is constructed the same as the M43, the only difference is how the submuntion was delivered. The Blu 18's were packed in Suu13 tubes and placed on aircraft to be dispensed. The M43 was dispensed threw 8in, 16in, and 155mm projectiles. The cheese wedge shape of the subminition made it easy to pack into tubes or projectiles. After released the vains or wings would open providing stabilization and arming would occur. Once the submunition came in contact with the ground it would fire is ball shaped grenade into the air where it would detonate around waist level.
SSU 13 Tube