The Midwest Industries Polymer M-Lok Rail Section models are as follows. Model number MI-5PMR is the 5 slot model, model number MI-3PMR is the 3 slot model and model number MI-7PMR is the 7 slot model. Choose the model that has the correct number of slots or length for the application you need.
The photos don't match the descriptions for the 5 and 7 slot versions. I needed a 7 slot and ordered it, but it shows a 5 slot in the listing. Guess I'll find out when it arrives.