What does "Equipment required - Reefer, Van 53 " mean?

LTL and serving the NYC area, 11 years ago when I came onboard we had NO 53's but all 48's.

The fleet grew, mostly buying 53's though we did add (4) 48' roll ups plus (2) 35' lift gates, a 45' lift gate and a 48' lift gate and the latest batch of 53's included a lift gate, go figure...everything else is a 53 and any of the old 48's still around are storage only.

OP by asking for 53' reefer or van they are saying that the load does not need refridgeration and is light enough to load on a heavier reefer but still needs 53' to fit the freight so it has the 'cube' to need the 53 but not sensitive to the overall tare weiight.