3-3/8" Gamet boring and facing head.  3/4" bars. ~1-3/4" max offset.
3 rates of feed.  

Note the photo showing the ramp cams in the knurled
hand ring: one cam is always up, and the apparent adjuster screw is
bored, without a hex.  The ramps are raised by the adjuster screws 
with hex sockets on the OD of the knurled hand ring.  The hex screws
are partially mille through on one side, under the ramps.  So in one
position, the ramp is held up.  In the other, spring pressure retracts
it.  If one ramp is up, the feed is (rated) .0025"/rev. 2 ramps up =
..005" feed/rev.  All 3 = .0075 feed/rev.  So it can be seen that feed
is neither continuous, nor, in the 2 ramp/.005 feed is it uniform.

The feed stop is a simple hardened cam with a small soft pin (for
overload release, i suspect).  When the adjustable stop hits the
pin on the outside of the head, the cut portion inside turns to 
bear against the end of a rod, that puts pressure on the shank of
the feed pawl, stopping it from moving.  Your hand on the knurled 
ring provides the friction/slip clutch.

Gamets are fairly rugged heads, but rather simply made, compared to,
say, a Wohlhaupter or D'Andrea.  The Gamets also only work with the
machine spindle turning clockwise (from above); and they don't 
retract.  To haul back to the starting point, it is necessary to 
use an allen key in the lead screw, as per a typical non-facing 
head.