Iron is a type of Force. Force is related to Wave. Wave is related to Frequency. 
Guarantee is a type of Back. Back is related to Reward. Reward is related to Benefit. 
Iron --IsA--> Force <--RelatedTo--> Wave <--RelatedTo--> Frequency 
Guarantee --IsA--> Back <--RelatedTo--> Reward <--RelatedTo--> Benefit 