Hasselblad 80mm CF extension tube

[6by6cm]

Hi all,

I am using a Hasselblad 80mm CF lens. I want to get an extension tube so I can use it for close-ups. Any ideas on what to buy?

Basically, what I need is to be able to go closer to the subject and do a tighter crop until I manage to get a 120mm. I will also use it for product photography. Right now, I could only crop to the chest level for portraits 'coz of the minimum focusing distance.

Thanks.