The part the is supposed to go inside the hose is too big. It has ridges. Is there a model with a smaller diameter?

Thank you for reaching out to us. This part is good for repairing both 5/8" and 3/4" hose. Some times it is a very tight fit when assembling and it helps to use some soapy water to slide the part into the hose. If you are trying to repair 1/2" hose this part will not work. If you have any additional questions please feel free to reach out to our office at 303-867-1537. Thanks!