Older model of dive alert horn - is it both above and below water?

[Sbiriguda]

I found this one
Dive Alert Scuba Signaling Device Power Whistle Safety System BCD attachment | eBay
The seller says it is both above and below water but I don't think so
For me it is surface only
Anybody knows this type of dive alert?
Thanks

 

[Sbiriguda]

I asked to check and the seller said he was mistaken...
It is surface only

 

[Sbiriguda]

I answer again to myself... apparently Dive Alert is now part of Scubapro company. So any authorized Scubapro retailer can have the dive alert horn or order it. For people who live in the US perhaps it's not a problem to get one but here in Europe it's not that easy to find them online