Pole Pigs

Hello Coilers,
First I would like to say thanks to everyone for the interesting dialog.
I have learned quite a bit over the last few months.
I have a couple of questions about pole pigs. What sizes are typically
available? I want to limit my power to 5-10 kva. Just how big are these
things (dimensions and weight)? As I drive to work I find myself eyeing
the poles where most of the pigs are 25kva. I also noticed that some 
installations go underground with the high voltage to a metal box, is there
an air cooled xformer inside? 
Thanks in advance
Dave Huffman