The 50 Watt Brennan BSP50 bookshelf loudspeakers are a perfect match for B3's size and power.
(NB Helix cannot drive loudspeakers directly)
Dimensions 22cm (H) x 14.5cm (W) x 18cm (D)
The speakers have a detachable black cloth grille and are supplied with a pair of 3m speaker leads for use with B3 [4mm plugs to bare wire]
This article explains how to connect BSP50s to a B3
BSP50s are sold in pairs - the price is for the pair.