Identify the type of contractual clauses that are evidenced by the following scenarios or extract from contract:

Kudu sells his erf with a house on it to Princess for R650 000. The contract is put into writing and signed by both parties. The contract contains the following provision:

"This sale is subject to Princess obtaining a loan for the purchase price within 20 days from the signing of the contract from FNB against security of a first mortgage bond on the land".