Constant MAX_MANDATORY_HEADER_SIZE 

pub const MAX_MANDATORY_HEADER_SIZE: u32 = _; // 122_880u32

Approximate maximal header size on Polkadot-like chains.

See bp_header_chain::ChainWithGrandpa for more details.

This value comes from recent (December, 2023) Kusama headers. Maximal header is a mandatory header. In its SCALE-encoded form it is 113407 bytes. Let’s have some reserve here.