These are special Venetian Plaster trowels that have a very thin flexible stainless steel blade, that are capable of applying plasters without leaving many lines. The blade is flexible enough that it easily glides over surface imperfections on walls and cuts application time down by at least half. Once these trowels were developed a few years back I never went back to stiff venetian trowels for my first coats ever again.
These are medium size trowels, 240 x 100 mm and have a wooden handle.