The cheap white type foam.
The cab itself was in a plastic bag.
When I got it the foam corners were obliterated.
They don't remove the tubes when they ship but they had spring retainers on the EL84 tubes.
A couple of the tubes were cockeyed but still in their sockets.
I was very surprised the amp even worked when I got it.
There were no marks on the cab.
I had a microphonic tube so when I called tech support I mentioned the corner protectors and that they didn't survive.
He says, were they the solid blue ones?
I said no, they were the regular white ones.
He goes, oh, you got one of the old ones.....
In my opinion, you can't pack an amp too good.
So maybe you can make your own corner protectors but use the rigid solid type foam found at Home Depot.
Double box it unless you can find a double or triple walled box.
It amazes me that as many amps survive shipment as they do, because not all merchants pack well.
I suppose they are playing the odds and save on packing and just pay for the occasional amp that gets borked.