In addition to 1911Terry's good info, Tanfolgio pistols were also imported as the TZ75, the TA90, the Springfield P9, and now the Witness, by FIE, Excam, and EAA, which is the survivors of those previous companies.
The Witness pistol come in two frame sizes, the "small" frame being convertable 22lr/9mm/40SW, and the "large" frame those plus 45/38 Super/10mm. I am pretty sure there is a 357SiG drop in barrel available somewhere. Hi cap mags are available in all calibers both new and used.
The Tanfolgio has sometimes been called the "CZ Improved", as it has several fewer parts than the classic origunal CZ it was cloned from. I had 6 Witness pistols, and every time one left, it was a financial decision - I would never have sold any if I didn't have to.
I am a die hard CZ man,(CZ75 PO1 favorite), and so is my wife, (CZ2075 RAMI 9mm for her), but we liked our Witness pistols very much. The CZ75B is an excellent pistol, and in any of its many incarnations will serve you well for a looooong time. Try a PO1 - you won't be dissapointed! Also, very soon, the new 40 SW Compacts will be coming out, in both alloy and steel frame, decocker plus standard C&L safety version. Enjoy!