I've used that exact one (the Fulton) and have had many years of good use. I actually have quite a collection because I bought some and then bought more when my local dealer got a batch in with the same key. I've used them on all the trailers, on all coupler types, and I've never had a problem.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9473.8 (as of 6/18/21)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR