This Subaru OEM turbo inlet is a plastic contraption that bolts to the air inlet of the turbo and accepts the stock compressor bypass valve (CBV). It is not uncommon for these to crack as they age.
This part uses an o-ring gasket to seal to the turbo, sold separately.
Fits all 2015-2021 Subaru WRX, and 2014-2018 Forester XT. (Specify model year.)