Rick,
Assume you are talking hole diameter as opposed to eyelet length. Only the 1/4 size (designated #8 here in the US) eyelet will work with the posts for attaching the TekLoks. 3/16 diameter has the #6 designation. Sample eyelet sizes are, for instance, 6-08, 6-10, 8-08, 8-10 where the first number refers to the diameter and the following number refers to the length.