Dont want to hurt his feelings

My partner finishes a bit too fast for my liking.. he once bought “special condoms” as he called them and he lasted super long.. I’m pretty sure they were the ones that are specifically made to help last longer but he hasn’t bought them since.. i tried saying “buy those special ones” and he had no clue which I was referring to, he came back with a variety pack that didn’t include the ones that help to last..my question is how do I ask him to buy the ones that make him last longer, I don’t want to be rude.. should I just buy them ahead of time? I’ve never done that before and I feel like it’d be obvious what I was trying to do but idk..