Window Glazing

Hello all, its me again. Thank you all so much for your help on the headlamps and the exterior crack solutions. I now have another dilemma, window glazing. I have narrowed down what fits due to the samples that I got from pelland. Problem is I do not know which part numbers they sent me. My question to you is that of measurements. Several of the same style beads have different measurments like 1/8 or 3/16. What is this referring to, what should i measure on the strips to determine which ones i need?