This prevents a bet being placed if the lay price is too far away from the back price. When there is low liquidity this can be a problem, lay prices may not present good value. Generally the closer to the race you bet, the better liquidity and tighter the spread.
Example 1 - Back odds 3.9, Lay odds 4.5, % back/lay ratio 10%
The calculation will be (4.5 – 3.9)/ 3.9 x 100 = 15% - the spread is too big so a bet won’t be placed.
Example 2 - Back odds 3.9, Lay odds 4.2, % back/lay ratio 10%
The calculation will be (4.2 – 3.9)/ 3.9 x 100 = 7.6% - the spread is within range so a bet will be placed.
Setting this to a large number like 500 will effectively disable it.
100% is default and fine for most markets, but you may want to filter some races
with low liquidity depending on the markets you are using.
