Looking for Battery-powered GPS Speedometer

[captmako]

Well, my airhead speedo is not at all accurate. I have an Iphone app. that gives accurate GPS-sourced speeds.
However, have not found a mount I like for the Iphone. So does anyone have any ideas where to purchase a small
battery-powered GPS speedometer? Googled already and did not see anything good.

[Kurt in S.A.]

Sorry, I don't know of any GPS devices. What about the Sigma speedometer?

http://www.aerostich.com/sigma-speedometer.html

Kurt in S.A.

[captmako]

Looks like a viable option. Thank you Kurt.

[blitz]

Here's one:

http://www.marineengine.com/newparts/pa ... Mgoda3IALA

Marine should be impervious to water.

Here's on for motorcycles:

http://www.dimecitycycles.com/vintage-c ... m2801.html