Softbox & Grid?
Going by the photo it looks to not be made specifically for a grid. But I have a Photoflex box that wasn't also, and just let the velcro mount for the diffuser share duty holding a grid on to it. That's my hair light box ( if I'm not using just a head with grid) and it works fantastically well.
But the next post down the list seems to have found a deal for a combo.