One Dog will work, two is even better...three; you can't get the Pharos in, or out, so a pair is the limit for one grinder!
This product is sold per one piece.
There are a number of central tenets that apply to all hand coffee grinders. First, more force is required for the grinder 'holding' hand, than the handle turning hand. The faster & more aggressive the grinding action of a particular grinder the harder it is to hold. Although the force required to turn the handle doesn't increase that much... So, as the Pharos is a very fast, very aggressive hand coffee grinder, when one uses it on the counter it can require a considerable amount of force to hold it steady. Most people accomplish this by forcefully pushing it down against the counter with the holding hand in the center, amongst the plates bolts.
We came up with the Pharos Bench Dogs as an assist in holding the grinder steady while in use. Very simply put, they are a sturdy L shaped bracket, specifically curved to fit the pad & plate of the Pharos. They can be screwed down permanently to a wooden counter top, butcher block, or screwed/bolted to a suitable board which is then clamped to your counter top. As with all of our modifications or accessories these do not change the basic design of the Pharos. They simply hold the grinder very steady and allow the amount of force, or grip needed to be vastly reduced. We use 2 - the most stable conformation, but one will work too.
We slide the grinder under the Pharos Dogs, hook a thumb around the opposing bolt cover at the middle plate, or lay the palm of the hand over the base plate and grind...when finished grinding simply slide the Pharos out, and proceed as usual. They really work great!
The original Pharos Dogs were milled from one piece of aluminum, we are re-issuing these, made in our workshop, in Idaho, USA, in American Red Oak with Black Walnut top, sanded & varnished - you provide the screws!
You can see how we use it here:
https://www.youtube.com/watch?v=asr4Nm9ooKo&t=5s