The latest model from my new TwinDiatonic series is now available to order: the TremoloHarp:
http://www.brendan-power.com/harmonicas ... remoloharp
The tremolo sound is not one I use but it's very popular, especially in Asia. Here it is available in a small 10-hole harp version for the first time, in 4 brands, any key you want including low keys, and with lots of alt tuning options as well. Enjoy!