Jinbei produces a number of softboxes for speedlites. This model is square sized and available in three sizes: 40cm, 50cm and 60cm. The images below show the 60cm version. The softbox is stored in a small bag which also contains a ball head and the flash holder. The flash holder is adjustable to your flash size so you can easily use small or large speedlites with this softbox. There was no issue mounting a Canan 580EX II including radio trigger to it.
Whats in the box:
2 white translucent front panels
Assembling is very easy. Unpack the softbox carefully, attach the flash mount and the front panels and mount it to a light stand. It is very important to unpack carefully. The softbox will unfold like a compressed spring and if you are not aware of this it will hit you. The whole assembling process does not take longer than a couple of minutes. While it is easy to assemble the softbox you'll need some training to disassemble it. The softbox uses a bending mechanism which is a little bit tricky.
Compared to my Flash2Softbox 50x70 Softbox I prefer the Jinbei model. It is easier to assemble and appears to be more durable. Of cause the flash holder and the ball head are not that well build but according to the price tag the build quality is fair. The softbox itself is well build and solid.