float, fire globe, target ball???

[bottlemania]

The guy had this labelled as a "float." It has a strange sealed top thing and is flat on the bottom. Also, it's not the color of most of the floats I see. Could anyone tell me if its a fire grenade or target ball, any approx value or any other info? It is sealed but has nothing in it. As always, thanks in advance for any info.

Paul

 

[GuntherHess]

size matters... how big is it?