Desi Betfair are the joint with which you can lay horses - www.betfair.com - and the divies you get depend on the odds of the horse. If a horse is say $2.50 on the tote, you may have to offer between $2.50 and $3.00 on average to lay it. Reversed, if you lay a horse at $3.0 it is the same as backing it to lose at $1.50. If you lay a horse at $10 it is the same as backing it to lose at $1.11. If you lay a horse at $2.00 it is the same as backing it to lose at $2.00.