Probe SRS forged pistons are designed for high performance street and most racing applications. SRS pistons are available in a wide variety of designs, tuned to achieve the highest performance possible. Any combination from ultralight 2bbl oval track to high performance street, to heavily boosted race only cars will find Probe SRS Forged Pistons to be the perfect piston. 2618-t61 Forged Aluminum. Lightweight wrist pins. Lightweight piston designs. Full floating wrist pins. Tight running clearances. Narrow piston rings. Low drag skirt design. Large variety of compression ratios. Design specific valve reliefs.