Reserva 51 Unica Extra Premium American Oak. Cachaca 51 are the market leaders of cachaça in Brasil (so you might as well say the world). Their standard Prata and Ouro cachaca’s are readily available, in Europe and the UK. I think they also may export to the US.
The Reserva 51 range is the companies more premium offerings. They have 3 cachacas in this series. They have this Reserva 51 Unica (aged in ex-bourbon casks), Reserva 51 Singular (ex-bourbon and Amburana wood) and a Reserva 51 Rara (ex-bourbon and ex-South American Wine Barrels). At the very top of the range they have a Reserva 51 Carvalho Americano (ex-bourbon)