However the rap4 one is a whole block, with a fixed pierce pin.
The seal is an Oring that goes around the nozzle in a Delta, but a flat washer that seals to the face on the rap4.
It depends on your 12grams. Some brands rip the Oring out after only a few cyls, others are ok. The faceseal type is far more durable, with a simpler replacement of the seal.
IF it doesn't give you trouble, you can stay with the stock type, but you have to open, clean and lube it with the rest of the pistol.
I just put a new block in a Delta68 sunday, I helped save an ebay victim. It was a block I made that takes Phantom pierce pins(faceseal type). A new cupseal and a shim spring added to the mainspring got it purring.
We play Pistol and we encourage the Few despite the discouragement of the Many.