Our KZ TT came with a Conntek cord and fittings. The threaded collar is awful and hard to thread on. Never use it and it's a spare stored inside. We use a Marinco (Park Power) 30 amp cord we already had which has a 1/4-turn locking ring and it fits the Conntek inlet fitting. The 1/4-turn ring locks quickly and easily into place. (It's actually a bit less than 1/4 turn). You can buy just the Park Power locking rings but can't remember if it slips over the plug end of the cord.
Another solution would be to get a Park Power right angle adapter pigtail with the 1/4-turn ring.