What is Conversion coverage in regards to insuring industrial rental equipment?

To be paid on a claim your policy must be activated by a "trigger" or a covered cause of loss. Fire, theft, smoke damage, etc. are all covered causes of loss.

As an equipment rental company your exposure is different in that you are "giving" your equipment to an individual/company for a rental fee. If they decide not to return that equipment you're out of luck. Your insurance carrier isn't going to consider this loss a "theft" since you willing gave it to them. Therefore, no coverage.

Conversion coverage provides coverage for those items you rent out in the event that they are not returned. If someone signs your contract, gives you a fake CC number and then dissapears into the night with you equipment you'll have coverage for the loss. Keep in mind though that these deductibles are typically high and may not make sense for you depending on the equipment you're renting out. If the majority of your items you rent out are ~$1,000 and your conversion coverage deductible is $5,000 why would you pay for the extra coverage when you'd likely never have a claim large enough to justify the $5K deductible.