Through many years as a bull with many couples nearly all the guys I've cuckolded were 4-5 inches. Although I don't have measurements on all the guys and this is an estimate, I don't think any cuck was smaller than 4 inches.
Years ago, an ex gf described the guy she dated before me as being shockingly tiny and thin. She estimated about 3 inches and so thin that condoms were an issue. Needless to say she was overjoyed with what I'm packing, and every time we had sex she was very vocal about size being a huge factor in her pleasure. I technically never cuckolded that guy, but ever since then I've wanted to find a cuckold with a micropenis.
Size has always been a huge part of the kink for me, and the bigger the size difference between me and the cuck the more it turns me on. The thing is, I'm not even really into hardcore SPH. I don't want to tease the guy or mock him. I want my size and my actions to do the cuckolding.
Fortunately for most men, but unfortunately for this fantasy of mine, legit micropenises seem exceptionally rare.