These fittings are equipped with a mechanical ground lug for external bonding of liquidtight  flexible metal conduit.

Three tapped mounting holes eliminate orientation difficulties during installation … the installer tightens the gland nut, and then installs the grounding lug in any one of the three tapped holes.

Either compression type lugs or mechanical grounding lugs can be used.

The bolt size is 3/8-16.

These new fittings satisfy the 1978 National Electrical Code, section 250- 79 (e) for external bonding of liquidtight flexible  metal conduit.