The H115i already comes with 2 x 140mm ML fans...
"Two low-noise 140mm ML Series magnetic levitation PWM fans deliver improved airflow and produce just 20 dBA of noise at full speed." They look like the ML PWM Premium fans, no LED's and grey (gray) blades.
I would point out that the ML PWM Premium fans purchased separately are rated at 37 dBA and not the 20dBA listed with the H115i or 25 dBA for the H150i. You would think the ML fans included are the same model as the ones sold separately, but they don't appear to be. I haven't taken my case apart to look at part numbers yet, will do this weekend.
ML Fan Specs:
ML Pro RGB LED, 25 (120mm) / 20.4 (140mm) dBA, 400-1200 RPM, 47.3 (120mm) / 55.4 (140mm) CFM ML Pro LED, 37 dBA, 400-2000 RPM, 75 (120mm) / 97 (140mm) CFM ML PWM Premium (grey blades), 37 dBA, 400-2400 RPM, 75 (120mm) / 97 (140mm) CFM ML Pro PWM Premium (black blades), 37 dBA, 400-2400 RPM, 75 (120mm) / 97 (140mm) CFM