These instruments combine a BOLT12 invoice_request on the front side with an offer on the back, facilitating a new way to conduct transactions without direct internet access. The process involves generating these requests in advance through software connected to a lightning node, which then encodes the data into QR codes. These codes contain URIs that denote the transaction details, allowing for easy printing and distribution.

The operational mechanism behind Lighting Cheques enables merchants to process payments by scanning the invoice_request, and subsequently issue change through the offer QR code. This system mirrors the tangible exchange of cash, offering various denominations to optimize transaction efficiency and minimize change-related risks. However, the model introduces a trust element, as users must rely on merchants to provide accurate change, akin to traditional cash transactions. A notable limitation is the delayed awareness of potential discrepancies until the payer reviews their account.

To address security concerns and enhance convenience, proposals include overprinting cheques for denomination flexibility, employing Faraday Bags for transport, and potentially integrating NFC technology for reusable formats. Additionally, the versatility of Lightning Cheques extends to gifting, educational expenses, travel safety, and providing a financial solution for individuals with limited access to mobile technology or those preferring physical transaction mediums.

For further details, refer to the original proposal on delvingbitcoin.org.