I wouldn't ship via DHL personally. They seem to damage a lot more than Fed Ex or UPS.

When I shipped the last set of heads, I took a piece of scrap 3/8" plywood and cut it larger than the footprint of the heads. I drilled 4 holes in it and than used large zip ties to fasten the head to it. Than just boxed it up normally. Kept it from doing any shifting in the box and potentially tearing out. The buyer sent a note saying he appreciated the extra efford in shipping prep. They came through with 0 damage.