Question about Comply Insulation Tx-200

Yes, they work. They are exactly the same as the ones Bang & Olufsen supplied with the Beoplay E8.
PS: I ordered them and I also have the Beoplay E8.

These attachments have an easily stretchable tube that is plugged onto the earpiece.

According to manufacture with the following diameters:

Width/Diameter at proximal end (end attaching to device):
Small: 10.67 mm ± 0.50 mm (0.420" ± 0.020")
Medium: 12.45 mm ± 0.50 mm (0.490" ± 0.020") -> Check your E8.
Large: 13.97 mm ± 0.50 mm (0.550" ± 0.020")

I am totally enthusiastic about these things, I can only recommend them.