The three horizontal bands encircling the vertical fasces on the reverse are often not fully struck, and are blended together. When all three sets are fully struck, divided, the coin is referred to as having "Full Split Bands (FSB)." Your coin demonstrates this strength of strike. A 1937 Mercury with Full Bands in MS65 is approximately a US$50 coin.
Mercs are out of my comfort zone for grading, so I won't attempt to offer an opinion. I would ask about the marks on the lower neck, though, to the right of IGWT - are they on the coin?