I have a few Bowens mount softboxes, including a Phottix 105cm (41 inch), which is a go-to for a lot of my photography. This Bowens mount was a total failure. First, the softbox does not fit securely to the mount -- there is no familiar 'snap' and only a single tightening screw that is not tight enough. Second, the softbox was too heavy; the vertical stem could not support the weight and would pull the adjustable portion down.
A third issue I had is that I intended to use this mount for securing the StellaPro Reflex to my lightstand rather than purchase the separate lightstand mount accessory. But this mount is so designed that I couldn't mount a bounce umbrella with it.
Bottom line -- I returned the Bowens mount and because I don't want to purchase new softboxes, I returned the two Reflex lights that I had also purchased.
With so many Bowen mounts out there it seems like a connector should be made that is strong and fits perfectly. This does neither. This is not capable of working with large softboxes. It doesn't tighten nearly enough. And getting the mount to connect with the softboxes is tricky as well.
A rep from Stella did reach out to me and help me with a fix to get the mount to work with one of my softboxes - a smaller one - but the work-around didn't hold my larger one. The lights are very expensive and the mount should be included with a kit. And for $99 I would think that the product would hold and be strong enough to hold larger softboxes.