Bearing savers degraaff SB750

[doggypaddle]

Anyone know what size bearing savers fit the above degraaff trailer?
there seems to be a wide range of sizes available in the right ballpark.
I measured the hub and its in the region of 50.5-50.6mm
savers are available in the sizes 50.25/ 50.5/ 50.73
don't know wether to get the 50.5 or 50.73.
i think 50.5 may be slack and the 50.73 seems like too much of an inteference fit.
anyone know for sure? i don't particularly want to have to turn them down or send them back if too small.

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[doggypaddle]

sorted now, its 50.5