Frequency	n/a (antenna mount)
Bands	n/a
Power	A passive antenna mount - it carries the antenna and feedline; power handling is set by the antenna and connector used.
Modes	antenna mount (NMO or UHF base; trunk/lip/hatchback)

Connectors

mount	Clamps a trunk lid, hatchback or door edge with four set screws (no drilling); 2-axis angle adjustment.
feed	Comes pre-wired: K400CNMO = NMO base + 6.5 ft PTFE coax to PL-259; K400SNMO = NMO base + 13.5 ft to SMA (UHF-base versions also offered).
power req	None - a passive mount.

Heavy-duty no-drill lip mount for trunk lids, hatchbacks and door edges Four set screws bite for positive grounding and to hold larger antennas 2-axis adjustment to set the antenna vertical on a sloped surface Rubber pad protects the mounting surface from scratches Recommended for large VHF/UHF and medium-size HF antennas Supplied pre-wired with C-series PTFE coax (NMO or UHF base; PL-259 or SMA radio end) K400C (6.5 ft) and K400S (13.5 ft) cable-length variants

Strengths

The go-to heavy-duty lip mount: four set screws give a solid grip and good ground for big VHF/UHF whips (and medium HF antennas), it installs with no drilling, and the rubber pad protects paint. It comes pre-wired with quality PTFE coax in your choice of base (NMO or UHF) and radio connector, so it is essentially plug-and-play.

Weaknesses

A lip mount is still a clamp-on compromise versus a drilled NMO hole for the very best ground and stability, the set screws can mark the paint edge under the pad over time, and you must pick the right base/cable variant for your antenna and radio. Heavy HF screwdrivers may exceed what any lip mount should carry.

Verdict

The Diamond K400 is the standard heavy-duty no-drill lip mount - solid grip, good grounding and pre-wired quality coax for large VHF/UHF or medium HF antennas. The default choice when you do not want to drill a hole; use a drilled NMO mount for the ultimate install.

The Diamond K400 is the heavy-duty member of Diamond's no-drill antenna-mount range, and one of the most widely used mobile mounts in the hobby. It clamps over the lip of a trunk lid, hatchback or door edge and is locked down with four set screws, which do double duty: they hold the mount firmly enough for large antennas and they bite through the paint to establish a solid RF ground. A rubber pad under the body protects the mounting surface, and a 2-axis adjustment lets you stand the antenna vertical even on a sloped trunk.

It is recommended for large VHF/UHF antennas and medium-size HF whips, and it ships pre-wired with quality C-series PTFE coax. You choose the base (NMO or UHF/SO-239) and the radio-end connector and cable length: the K400CNMO pairs an NMO base with 6.5 feet of coax to a PL-259, while the K400SNMO uses 13.5 feet to an SMA - so you can match it to a handheld, mobile or base radio.

The trade-offs are those of any clamp-on mount: a drilled NMO hole still gives the best possible ground and mechanical stability, the set screws can eventually mark the paint edge, and you must order the variant that fits your antenna and rig. For a no-drill install of a sizeable antenna, though, it is the benchmark. Compare it with the medium-duty Diamond K412 and pair it with a mobile whip like the Diamond HF40CL.

Diamond K400 (Heavy-Duty Trunk/Lip Antenna Mount)