Speaker dimensions: 40 x 7.2 mm. Length of boom microphone: 190 mm. Cable length (speaker - speaker): 555 mm. Weight main module: 64 g.

Official data from Sena. Compatible with my helmets: Shoei GT-Air 2 and Shoei NXR 2

The speakers have a diameter of 40 mm and are approx. 7 mm high
Mounted in the following helmets: Shoei GT-Air, X-Lite 1005 Ultra Carbon, Shark Evo One 2, Nolan N80-8.
The sound quality is better than HD quality, bass is significantly deeper, volume is fine.
Sufficient for phone calls on motorway journeys (keeping the legal speed).

I don't know..not worth buying...no noticeable improvement in sound quality...much too quiet even with headphones

Exciting I briefly measured my earphones and came up with ~4.5cm
There is still foam around the earphones, so the measurement may differ in the millimetre range. For me, they don't fit into the bulge in the helmet because of a few millimetres, but they work wonderfully and I don't feel them when I wear them.