An 8 mm rubber grommet listing needs a defined dimension: 8 mm may refer to the bore, mounting hole or another feature. The nominal size does not determine the whole profile.
Cable protection
A panel grommet helps protect cable insulation from damage at an opening. Its function is not to stop current flowing through the cable. It also does not, by itself, establish a dustproof or waterproof enclosure.
Check the actual construction
A rubber panel grommet may use a retaining groove and flanges. A furniture cable outlet with a rotating cap is a different product arrangement; that construction cannot be inferred from an 8 mm size description.
Confirm the drawing, panel-thickness range and cable clearance. Then specify the compound and operating conditions. For a custom part, submit a customer drawing or sample for manufacturability review.
