This lens is one of the smallest and lightest M42 lenses. It measures just 55mm in height (with rubber hood - barely 32mm without!) and just 45mm in diameter, 146mm in circumference. Very sharp at all apertures, but has quite a long minimum focus distance (about 100cm) which means it is NOT very suitable for macro work. The hood easily slides off, but is solid once put on.
Do NOT confuse this with the other Curtagon 35mm 2.8 lens available, which is much older, larger and heavier.
This is the C-Curtagon, or 'baby C'.