| Phone weight | Check the phone’s listed mass, including its case and any attached metal ring. | Many smartphones weigh roughly 150–250 g; accessories add weight. | A heavier phone increases the load on both the magnetic connection and the suction base. |
| Static phone load | Estimate weight force as mass in kilograms × 9.81 m/s². | A 200 g phone produces about 2.0 N of static weight force. | This is a baseline only; bumps and vibration can create higher short-term loads. |
| Magnetic pull force | Look for a force measurement in newtons (N) and check how it was measured. A straight pull-off test is different from a sliding test. | Compare results only when phone or test plate, contact area, and pull direction are similar. | A high normal pull-off figure alone does not establish resistance to sideways sliding or twisting. |
| Magnetic shear and alignment | Test whether the phone slips or rotates when mounted vertically and when the mount is gently disturbed. | Use the intended phone and case; magnets, metal rings, and contact surfaces vary. | A centered, flat magnetic connection generally reduces wobble and uneven loading. |
| Vacuum-base seal | Check that the suction cup sits flat, the locking mechanism engages, and the base does not leak or lift at the edges. | Smooth, clean, nonporous surfaces are generally more suitable than textured, dusty, or porous ones. | A strong magnet cannot compensate for a weak or incomplete suction seal. |
| Surface compatibility | Confirm the intended mounting surface is smooth, clean, dry, and large enough for the full suction cup. | Curved dashboards, seams, soft-touch finishes, and textured trim can prevent a reliable seal. | Surface mismatch can cause gradual detachment even if the mount initially feels secure. |
| Arm length and joint stiffness | Check for movement at hinges and joints after setting the phone angle. | Longer arms create more leverage at the base than shorter arms under the same phone load. | A short, firm arm usually reduces vibration and the tendency of the base to peel away. |
| Road-vibration check | After installation, check for phone movement, joint loosening, or loss of suction during normal use. | There is no single vibration result that applies to every vehicle, surface, and phone setup. | A stable setup should keep the phone aligned without visible sliding or repeated readjustment. |
| Overall selection | Evaluate the magnetic connection and suction base together using the actual phone, case, and mounting surface. | Prefer clearly stated test conditions, a secure seal, and a phone connection that resists both pull-off and sliding. | Choose the setup that remains secure in the intended orientation, not simply the one with the largest advertised force figure. |