954 Hi Candice,
Welcome to the site. I would recommend the dogtra 2300. I have one listed in the recommended training tools at the bottom of the page. The 175 can sometimes fall short of what you need if your German Shepherd gets highly distracted (with the combo of the long hair) and the dog wont react. The other plus with the 2300 is that it charges in 2 hours as opposed to 14 hours, and there is a digital display on the controller so that you can better fine tune the stim.
For contact points – be sure to obtain 3/4 inch points. That’s what we use at the kennel for all shepherds.
There are other models that will work too, but the 2300 has the best combo of useful features for the price and is very versatile whether using it for in the home or out on a hike.
Any questions let me know…