50T and 52T > 5-hole sprockets > 2 for the price of one
Here's a 5 hole Freewheel hub sprocket deal;
(2) chrome (5) hole sprockets for the price of one.
50T concave sprocket has (5) slotted and (5) round 6.5mm dia. holes
52T flat sprocket has 5 holes 6.5mm dia.
The Big center hole in both sprockets is 63.6mm dia. Should be 64.00mm dia. to fit Freewheel hubs, so may require slight sanding or filing to fit nicely.
The (5) 6.5mm holes on both sprockets are on a 80mm circumference.