The red tool has two sides and will fit most nut sizes that are commonly used. If in fact you have a nut that the wrench will not fit then your only solution is to use a larger wrench. For help or additional questions contact Fluidmaster at fluidmaster.com/support to email or chat with an agent or call toll free at 800-631-2011 to speak with an agent. We are available from 5:30am to 5:00pm PST Monday thru Friday.
