The clever lads at maver has just released a new micro bore pole bush, it is a bush with a 3.8mm outside diameter, that is size 5 in the maver range, but instead of the usual 3.5mm inside diameter it has only a 2mm inside diameter.
This allows you to put fine elastics in your power kits without the connector getting stuck in the larger bush. Before these became available I used to stick a size 2 bush inside a size 5 bush to achieve the same effect.
Another advantage of this bush with fine elastics is that it keeps the elastic away from the inside wall of the top kits and because of the large bore of a power kit instead of a match kit there is a lot of 'air' around the elastic, so that it goes in and out easier.
For more information on prices etc click on Maver Micro Bore Bush