Rabbi Aryeh Lebowitz

You need a prusa, because that's lechem oni.

A broken piece is lechem oni.

That's your mitzvah v'akhilas matzah.

So you have to have a kazayis from that.

Why do you have a kazayis from the whole matzah?

That's for your regular lechem ishna, for your regular sudas yantiv, you made a bracha, v'amotzi lechem in haaretz, so for the bracha, v'amotzi lechem in haaretz, you have from the regular piece.

That's assuming that the normal shiur for the bracha v'amotzi, for sudas yantiv, is a kazayis, right?

That's the shiit of the Rosh, and the Mordechai apparently, it's in Simireish Sadialet in the Mishra Barua,

He says that for a Shudas Shabbos Yontav it could be that you need a kibbeitza, not just a kizayis.

But at least with this, with this chumrah, of having two kizayis, we're not going to be in Machmir.

They have to have a kizayis plus a kibbeitza.

Okay, good enough, they have Shnei kizayis.

And the Rosh HaMorach I explained, because if you were to have it all in one, it was just one big kizayis, then it would be a violation of Eidos and Mitzvot Chavilos Chavilos, that have both Mitzvot, both the Mitzvot of Shudas Yontav and the Mitzvot of

on the same chazayis so we separate them from the prusa you have your achilas matzah from the shleima you have your suddha shabziyantiv and we're making that the shleima only needs for suddha shabziyantiv you only need a chazayis gives another reason to have two chazayis he says you should need a chazayis from the prusa samotzi so kol bracha is each bracha is its own chazayis

Again, it seems to be really the same reason.

But each bracha requires its own kezai.

Piral Lacha just wonders in Simitav Ainei, Devor Maschel, Kezai is Mikal Lacha.

He says, this is highly unusual.

The whole sugya, the Gemara, keeps talking about

eating kezayis matzah, asha mishachal kezayis matzah, below ha-seba, is he yodzeh, is he not yodzeh?