Two Versions of SMA?
We ONLY sell the SMA 820S with the o-ring. There are two versions of the Remtronix SMA antenna: with o-ring (820S) and without 0-ring (810S). Besides this, they are exactly the same and get you to the same place. We have tested both and there is no difference.
An older version of the SMA (800s) Remtronix antenna would not screw flush with the pin, leading to intermittent signal, but this is no longer an issue. Remtronix updated the SKU specifically to accommodate the Uniden SDS100.