Impact Speed Ring for Lowel Tota-light

In my concern about heat and fire risks, I may have overlooked your real question: whether or not the speedring will actually fit the softbox. I don't know the answer to that. It might, as most speedrings are pretty much the same size. But I recommend you call B&H sales support. They're great at answering this sort of thing.

If the rings are the same size diagonally from rod plug-in point to plug-in point, it is probably physically possible to make this substitution. However, you will have to use one of Photoflex's softboxes which are constructed to be heat resistant. I bought an Impact kit of two large softboxes with rings and stands from B&H earlier this year because the Photoflex softboxes I own are for strobes and could never stand the heat from the 750watt quartz lamps in the Tota lights. The Impact boxes are constructed of fairly heavy material and actually have vent flaps in the side walls to let heat escape. I see that Photoflex offers at least one softbox meant for hot lights, but having never used it I can't offer any input on comparison with the Impact box. If you are looking to use an existing Photoflex softbox which is actually meant for strobe use, you may be flirting with disaster. I hope this helps.