Caldercraft Model Boat Fittings 8110DW 10mm Double block. Walnut.
Sold In packs of 10y, these double blocks measure ((h) x (w) x (d)) 10mm x 4.7mm x 5.1mm and are available in walnut.
Equivalent manufacturers part number cross references:
Caldercraft 8110DW
Mantua 37080