Because this says etrex and looks super secure ie not held on with zip ties what could possibly go wrong?
Turns out its for eTrex H, Summit, Venture, Legend, Vista series and I have got 30x.
In engineering terms it is a thing of beauty. The tooling must have cost a fair bit and the cover has the thinnest O ring I have ever seen.
£8 posted or swap for etrexNx mount - yeah the one with zip ties.
Will add photos later.