Maha C401FS from Eastgear. That's the one I'd recommend, though a lighter alternative is one that they don't seem to sell anymore, one that's sourced from Taiwan. The latter has a foldable US-style twin prong on the unit itself, that can be plugged into any bathroom shaver point.
I have both, and they work well ... haven't "cooked" any of my batteries yet.
Go and have a look ... the "brick" power supply of the C401FS is surprisingly small and light. However, I think it only comes in the 2-round-pin configuration, so you may need an adapter with you when travelling (or fall back on the standard shaver outlets in hotels).