The larger striker in the photo above is for 22XX and Discovery. It fits all standard 22XX CO2 models and it's notched to work with Discovery and 2300KT / 2400KT breeches.
The smaller striker is for 1377, 1322, 2289G Backpacker and PC77. It does not work with the older 1377 and 1322 models that have a sliding breech cover.
The striker pin is interchangeable with both strikers.