The explanation of process safety protection layers and related probability of failure does not need to be complicated. This article shows visuals that can be used to explain the complexity of safety layers and their relationship to reduce the risk of an overall incident. It is proposed that the "Swiss Cheese Model" be replaced with a more realistic probability wheel referred to as the probability circular ruler, leading to usable information to be included in the P&ID as tagging labels with safety data of the process protecting device. (C) 2016 American Institute of Chemical Engineers