There were no details of the fixing bracket prior to purchase, which made it difficult to decide whether it would work with my speakers. While the options are quite flexible, I needed to buy some additional bolts and nuts. It'd be great if the seller uploaded the fixing details, which are included in the packaging. In the meantime, perhaps I can help address that shortcoming.
The top of the stand has a couple of options.
The first is a small triangular platform on which the speaker can simply be placed, without fixing. The triangle has rounded corners but if they were sharp, each side would be approximately 95mm. I didn't use this because I wanted something more secure.
The second option is a 'L' bracket, with fixing holes. It can be oriented horizontally or vertically. There are two sets of mounting holes, The smaller is based on a hole size of 5mm and is a single hole and slot with a spacing range of approximately 30-35mm. The larger is based on a hole size of approximately 6.5mm and has a slot/hole/slot combination, with the hole-slot spacing range of approximately 28-36mm (total range from slot to slot is double that). [A picture from the seller would be worth a thousand words of my description!]
There are a few supplied fixings, for speaker fixing, as follows (from the packing list):
M5 x 12mm screw
M6 x 12mm screw
1/4" x 1/2" UNC screw
1/4" x 1/2" UNC screw & thumb wheel set
Unfortunately, the fixings for my speakers were brackets with 4.5mm holes, so I needed smaller bolts/screws than had been supplied and nuts (and potentially washers too), or drill out my speaker brackets (which I didn't want to do). Not a big deal but over 6 quid from my local DIY superstore (usual rip off prices) which does affect the value of the stands.
One other note about the internal speaker wiring. I use 1.5mm2 3 core flex (could use 2 core, since I don't use the earth wire. I wasn't sure this would fit up the stand upright but it worked fine, although a little fiddly to use such a large cable.
I only assembled and tried the stands yesterday but, overall, they seem ok.
Hope this helps someone else.