Hi Mellie
Please excuse the wait. Here is the direct link to the kit suitable for your Roomba Combo i8;
iRobot Roomba Combo retrofit kit series i/j (1 piece)

Best regards,
Your iRobot Team

Hi Mellie_Jay
Thanks for your question. The article is coming in soon and should be available here soon. We'll get back to you as soon as it's ready. Hope that works for you
Best regards,
Your iRobot Team

Unfortunately, we do not offer the desired replacement items, so you would have to contact the manufacturer for this.