US Cluster Adapter, Mk 4 Mod 0
The Cluster Adapter Mk 4 is a simplification of the Mk 3. It employs only the band and pistol release device to hold the bombs together. With the bombs clustered together, one of them is then suspended from the bomb rack by its suspension lug. The nose-fuze vanes arc held stationary by two clips which are attached to wire springs. These springs are held between the bombs until the cluster opens, after which they are sprung free.
Collaborative Ordnance Data Repository