Haida vs Lee

Quick 3 questions please:

When I look at photos of the big and little stopper from Lee, they have a foam ridge around the edge.
When I see photos of the Haida - I didn't notice such a thing
Is there any pro/con for such a thing?

Does Haida make its own holder? Is it worthwhile? Will the filters fit in a Lee setup too?

how thick are the glass Haida filters - 2 or 4mm?

Thanks

The foam is to make a seal and block out the light. I haven't used Haida but my big stopper is pretty awesome.

I have a HiTech 10 stop filter that fits the Lee system, and it has a gasket seal, too. The Big Stopper was on a long backorder when I bought the HiTech.

haida's are probably more like 1.5mm (even the lee big stopper is less than 2mm I think, however their polarizer is 2mm and fairly hard to fit). Haida does have the foam ridge, but you have to apply them on yourself. it's easy to do and they give you two of them. You definitely need them to prevent light leak.

Filters fit fine on the genuine lee. Haida > lee imo. I still own a mixture of both lee and haida filters, and haida's are more closer to true neutral, and closer to exact 10 stops. Lee is closer to 11 stops, so I typically underexpose with it when I do shots based on calculations.

hitech is not an option, cast is really bad. Their 3 stop rgnd is fine, but that only filters 3 stops. When you do 10 stops, that's significantly more stopping power, so color cast is much more magnified.