Look, all I can really say is the Aeropack retainers are the best. Sure there's lots of ways to hold a motor in place that are cheaper but this is for 98mm motor. You're obviously spending some serious cash at this point. Retain your motor like a boss! There is a another brand of threaded retainer for 98mm but it uses fine threads. These coarse acme looking threads won't get buggered (I have some of the other brand retainers...) buy once, cry once!