Fir Audio Radon 6 is a limited flagship-level IEM by the American manufacturer. It uses a single Kinetic Bass DD driver, 4 balanced armatures and a single electrostatic driver. It's priced at $3299.
Fir Audio Kr5 is the mid level of Fir's newest series called The New Frontiers. It uses a dedicated dynamic driver for the bass and four balanced armature drivers. It packs some great technologies, and it's priced at $2999.
Fir Audio Xenon 6 is the flagship of the new Frontier Series from this American manufacturer. It’s a tribrid construction starting at $3899.