A signal-level board-to-board header at 1.25mm pitch
A built-in board guide on the housing helps register the header during reflow, reducing tombstoning risk on the pick-and-place line.
SMT termination and the board assembly fit
Surface-mount termination suits automated assembly, but the 1.25mm pitch requires a solder paste stencil with tight aperture control to avoid bridging between adjacent pins. The header ships in bulk, so you'll need to handle it with a tube or tray feeder — no tape-and-reel packaging is listed. In a mezzanine configuration, the mating receptacle's height plus this header height defines the total board-to-board clearance — budget accordingly in your enclosure z-height.