The amount of the first payment, except in special cases, such as unimproved, suburban, and subdivision properties, should usually be a fixed percentage of the purchase price, and sufficient to cover several monthly instalments. No uniform rule as to its amount can be laid down, but several large concerns doing business in the Southern States require 10% of the purchase price to be paid in before contracts will be executed. The rule is based on the belief that, if a purchaser cannot now, or in the immediate future, pay this 10%, he probably will be unable to meet regularly the future payments. The system has yielded excellent results, and has led to the use of options, such as shown in Section 130, which are available when a desirable purchaser requires a little time in which to make the first payment.