Master Lock - 6 Trailer Locks Keyed Alike 6KA-37937-37 Total trailer security Keyed Alike - One key opens all six locks. Multiple 6KA trailer lock packages CAN be keyed alike. If you ordered a quanity of 2, 3 etc we would automatically key them all the same. Latch lock doesn't fit some 2-5/16" couplers. See description below for latch lock (#37) applications. Each lock comes with two keys, for a total of twelve keys. Coupler lock fits 1-7/8", 2" & 2-5/16" couplers.