This is the Sea & Sea YS-D1/D2 100 Diffuser for Strobes Features: oftens the light of your flash, making it less harsh and reducing reflection for better image quality. Increases the beam angle of your YS-D1 strobe light from 80 x 80Adeg to 100 x 100Adeg. Gives the light a color temperature of 5250K. Provides a guide number of 24 on land at ISO 100. Best used when you want an even, strong, circular light output. Sea & Sea YS-D1, YS-D2 100 degree diffuser SS-28111