Coherent 25/400 Ytterbium-doped double clad fiber is ideally suited for high average power pulsed and narrow linewidth CW fiber amplifier applications. Based on a "few-moded" waveguide structure, this fiber is incorporated into components and monolithic designs where maintaining beam quality can be more difficult. In addition to the standard active fiber, Coherent can supply a matching passive support fiber for component and pigtail development efforts. As with all Coherent standard Large Mode Area (LMA) fibers, these fibers are proof-tested to 100 kpsi, an industry requirement for long term reliability when coiling for mode filtering.