Your spacer will be made of Padauk wood. Pterocarpus is a pantropical genus of trees in the family Fabaceae. It belongs to the subfamily Faboideae, and was recently assigned to the informal monophyletic Pterocarpus clade within the Dalbergieae. Most species of Pterocarpus yield valuable timber traded as padauk (or padouk); other common names are mukwa or narra. The wood is marketed as amboyna when it has grown in the burl form. The scientific name is Latinized Ancient Greek and means "wing fruit", referring to the unusual shape of the seed pods in this genus.