How Financing Details Affect Your Offer
A financing contingency in your offer protects you if interest rates suddenly become volatile and rise quickly. By adding a maximum acceptable interest rate in your offer, you are protecting yourself from such an occurrence.
At the same time, the seller will probably want to see that you have some flexibility in the financing terms you are willing to accept. If interest rates are currently at around 6% and you indicate this is the highest rate you will accept, you would be able to cancel the contract without penalty if interest rates rose past that point. The seller would suffer because they have lost valuable marketing time and may have made their own plans based on successfully closing the transaction.