1  In this paper，the author introduces two transfer fucntions of the RCCISD. The first one is transfer fuction using the shake table test data (see section 4.2 ). The second one is transfer fuction using sinusoidal calibration data(see section 4.3 ).  There are difference between these two transfer fuctions, especially from bandwidth 0.1Hz to 10Hz. Why use these two transfer fuctions in this paper?  Does these two transfer functions have an impact on subsequent gravity acceleration measurements and experimental data analysis?  

2 In section 4.4, during the experimental, where is the RCCISD? Be placed inside the vacuum chamber of the gravimeter? Or just be placed on the ground outside the vacuum chamber of the gravimeter?   When the RCCISD was placed on ground outside the vacuum chamber of the gravimeter, Is the vibration acceleration data measured at different positions consistent?  See following figure, near the A-pillar or B-pillar in the figure, the amplitude of vibration acceleration may be larger?  In the figure, the vibration amplitude at the center position of the four pillar A, B, C, and D is smaller.  But the small changes in the vibration acceleration signal measured by RCCISD may have a significant impact on the analysis of the gravity acceleration results of the gravimeter.

3 There are some unclear sentences in the article that need to be carefully revised.

This work develops and characterizes an open-loop Reference Corner-Cube Inertial Suspension Device (RCCISD) that hangs the reference retro-reflector of a laser-interferometer absolute gravimeter on a force-balanced pendulum. The authors report a ≈40 dB reduction of reference-cube vibration above 7 Hz compared with a cube placed rigidly on the pier, while shrinking the isolator to one-third of the FG5 “Super-Spring” size.

I have some comments and questions:

1. The authors performed sinusoidal shaker tests over 0.05–10 Hz at 17 discrete frequencies and obtained a fitted sensitivity of 387.7 V·m⁻¹·s; I think it’s important to include uncertainty bars on the Bode plots and to discuss the long-term stability or drift of this calibration constant—could you provide those details?
2. Which mechanical component gives rise to the ~150 Hz resonance peak, and is there a way to damp it without compromising low-frequency isolation?
3. Regarding thermal stability, I was wondering whether you have measured how temperature affects the suspension’s natural frequency (i.e., the flexure stiffness) as well as the voice-coil/magnet sensitivity.
4. Have you characterized the attenuation of horizontal vibrations (and any cross-axis coupling into the vertical measurement) ?
5. Have you measured the sensitivity of vertical acceleration read-out to horizontal tilt of the suspension frame?
6. A similar idea, suspending the reference cube using a pendulum or spring, may have been explored before in the context of passive vibration isolation systems. It would be interesting to see a comparison with any prior systems, if they exist. How does your approach relate to or differ from those?