Zscaler This document defines two post-quantum hybrid key exchange groups for TLS 1.3 that combine ML-KEM-512 with ECDHE: MLKEM512X25519 and SecP256r1MLKEM512. These groups provide lower-overhead hybrid key exchange options for deployments where ClientHello size, fragmentation risk, constrained-device performance, or compatibility with existing network infrastructure are important considerations. The groups defined in this document are intended for use with TLS 1.3 and DTLS 1.3 and follow the hybrid key exchange construction used by ECDHE-MLKEM key agreement for TLS 1.3.