This is a Stoptech ST40 caliper as pictured. The two bridge retaining bolts are missing and so is the brake pad clip that goes in the bridge but these are easily sourced from StopTech for not much money. I'll need to verify the piston sizes before you order but I believe they are 28 and 34mm. The caliper is setup to be used with a 32mm wide rotor. This appears to be a left side caliper when mounted on the trailing side of the wheel as the larger piston would be on top in this orientation. You can easily take the bleed nipples and the crossover tube out and swap the top to bottom to use it on the leading edge of the wheel if this is how your mounting system is setup. Retail for a new caliper is over $700.
Below is some basic info about StopTech calipers .
StopTech® 2-piece calipers have the lowest amount of flex and deflection among 25 of the leading caliper models (including some monoblocks) from well-known manufacturers. This is accomplished using StopTech's® patented bolt-in bridge, which is strong enough to stop distortion without sacrificing cooling through the top of the caliper.
The standard StopTech® caliper finish is a glossy high temperature paint available in one of six different colors - red, black, silver, blue, yellow and gold. Trophy Sport and Trophy Race Big Brake Kits use weight-optimized STR calipers finished with a deep natural anodized coating that resists fading and discoloration at extreme temperatures.