Caldercraft Model Boat Fittings 8105SW 5mm Single blocks. Walnut.
Sold in Packs of 10, these single blocks measure ((h) x (w) x (d)) 5.1mm x 2.4mm x 3.5mm and are available in walnut.
Equivalent manufacturers part number cross references:
Artesania AL8518
Caldercraft 8105SW
Disar Models DM11002
Mantua 37010