This is a terrific jacket - I think it was once part of a suit, but the pants are long gone and it looks just fine as a sport coat. 55% silk and 45% wool. I'm not sure just what to call that pattern, though, it's not a bird's eye, maybe a pindot? I dunno.

Two button front with four on each sleeve, notch lapel, double vented, the standard three pockets on the outside and four on the inside, moderate padding in the shoulders.

It's marked 52R, but that's the European measure. Common practice is to subtract 10, getting 42R, but I've been told that the more accurate approach is to multiply by .79. That gives 41.08.