The phrase "substantial guarantee" is grammatically correct and can be used in written English.
You can use this phrase when you want to describe something that provides a strong or significant level of assurance or protection. Example: The company's investment in the new security system was a substantial guarantee that their data would be protected from cyber attacks.
Seeking toraise money to buy another paper mill,he hit up both Sotheby's and Christie'sfor substantial guarantees.
He dislodges works from collections through dogged persuasion, sometimes with substantial guaranteed prices backed by Christie's or by a third party.
Seeking to raise money to buy another paper mill, he hit up both Sotheby's and Christie's for substantial guarantees.
Although the traditional tournament circuit was avowedly amateur, leading players were paid substantial guarantees "under the table" in addition to expenses.
Any driver who challenges a parking ticket — in person, in writing or online — is offered a substantial, guaranteed reduction for most fines, under a program the city quietly introduced in 2005.
As it did last spring, Phillips has given most of its sellers either substantial guarantees -- an undisclosed sum promised to a consignor regardless of a sale's outcome -- or other financial incentives to get their business.
One way is to create a couture image, which Phillips has done by luring the art world's equivalent of beautiful models -- from Cezanne, Renoir and Picasso to Damien Hirst; by making substantial guarantees to sellers; and by buying at least 8 of 31 works outright for resale, which is raising eyebrows.
In order to fund the advances and to build our service, we raised a number of rounds of capital and negotiated commercial agreements that contained substantial guarantees and advances with device manufacturers and network operators, who like us, understand that truly unlimited music is insanely valuable to consumers".
