Axle: 7.9mm QR Type (Suit Brompton). The SP SV9 is one of the smallest Dynamo hubs on the market. SV9 hubs are now labelled as 6V 1.5w. This is to comply with the strict German StVZO regulations. When used with 26” or 700c wheels the output can drop very slightly below 6V3 W at low speeds, but is 6V 3W at normal riding speeds.
eBay