which Ph pen?

Im looking at buying one and not really sure which one is good. Any suggestions? Thanks.

http://cgi.ebay.com/New-Accurate-DIG...QQcmdZViewItem

http://cgi.ebay.com/Milwaukee-Digita...QQcmdZViewItem

http://cgi.ebay.com/NEW-Milwaukee-pH...QQcmdZViewItem

http://cgi.ebay.com/NEW-Milwaukee-pH...QQcmdZViewItem

this is what I have...if that helps. and I bought a Milwaukee SM-301 for my EC meter...I feel that Milwaukee is superior to Hanna...peace

Hey Lw, i just got a MIlwaukee Ph51. I was wondering since you have the same meter, is it absolutley necessary to have the storage solution to use it? My manual says to soak the electrode in storage solution MA9015 for 2 hrs before using. And also, am i reading correctly that the meter must be stored with solution in the cap?

I bought mine used I would try it. water is usually 7.0

just soak it in water(I don't think you need that solution)...I store some water in cap to keep electrode filter wet. I would ask a hydro shop guy...I am sorry...I know I recommended that pen, but I got mine used off ebay 1-1/2 years ago and never have used the calibration solution...It came calibrated. let me know if this helps...If not I will look into it, by asking a hydro store friend...peace
p.s. I have dropped mine and all kinds of stuff...It has held up over time, and my hydro store have totally switched to milwaukee after having alot of service problems with Hanna...