This is an extracellular cadherin (EC) domain which can be found at the N-terminal region of Protocadherin 15 (Pcdh15). Pcdh15 features exceptionally long extracellular domains containing 11 ECs. These repeats are structurally similar, but not identical in sequence, often featuring linkers with conserved calcium-binding sites that confer mechanical strength to them.
Jiyao W et al.(2023). "The conserved domain database in 2023.",