Unless you have a ACH2000 (MICH), you pretty much have to go with either a soft (all webbing) mount like the PRR or one that doesn't go under the helmet. There are a couple that either go behind the neck or over the helmet. The PASGT/LWH suspension doesn't work well with under the helmet mounts. The OA BLSS system pretty much has the same problem because of the suspension ring used, their BLU kit on the hand is attached right to the helmet with Velcro similar to the way the ACH 2000 mounts its pads. With the BLU upgrade you can use a LWH or a PASGT with small under the helmet head sets, however you have to make sure the ear cups still fit.