More info on this lens please

[Lethagized]

Can someone give more info on this lens please and what sort of price it would sell for. Would it fit a modern canon ok? What is the extra black tube for?

Sigma 300mm 2.8

 

[Lethagized]

Thanks very much for the info gents. The lens was for sale in a local second hand shop in town. It's now sold on ebay for £180ish