Sotheby’s will auction off five unique Bang & Olufsen BeoSound 1 speakers this week, which the two companies are calling a celebration of the art of design. Each speaker has been individually anodized and dyed at B&O’s world-leading aluminum factory in Denmark. This is what makes the pieces genuinely special: Bang & Olufsen fancies itself the best company in the world when it comes to crafting aluminum (its high-profile clients like BMW would agree), and it achieves a level of design precision that’s rarely matched. You certainly couldn’t just buy a generic BeoSound 1 and spray-paint it to look like one of these special one-of-a-kind editions.

Originally produced to mark the 2016 launch of the BeoSound 1 360-degree wireless speaker, the five distinctively colored pieces are going up for online auction this Thursday, with an estimated final cost of somewhere between $3,000 and $5,000. That’s double and triple the original price of $1,495, which was in itself a steep hill climb for a Wi-Fi speaker.

I reviewed the larger BeoSound 2 last year and really enjoyed its warm and friendly sound, though not to the degree where I would recommend it as a rational $1,995 purchase. The BeoSound 1 has the advantage of being nominally portable — with a built-in 16-hour battery — though reviews of its sound quality and performance don’t describe it as being the truly hi-fi product that might justify its price in functional terms. No, if you’re buying one of these B&O speakers, you’re doing it for the looks, the precise engineering, and, in the case of these five unique examples, the knowledge you have a thing inscribed with “1/1” to signify its exclusivity.