Buying sights can be confusing but we at Lone Wolf are here to help.

It is our experience the following work best in most cases:
+0 (6.5) works best on 9/40/357 guns except the 26,27,33
+1 (6.9) works best with 10/45 guns and the 26,27,33

Glock Number to Aftermarket Number Chart:
Glock Factory  6.1    =    -1 Aftermarket
Glock Factory  6.5    =    +0 Aftermarket
Glock Factory  6.9    =    +1 Aftermarket
Glock Factory  7.3    =    +2  Aftermarket
-1 (6.1) and +2 (7.3) primarily used for sight adjustment.  

Sight Adjustment:  
Adjust the rear sight in the same direction you want the bullet impact to move.
Each sight height will result in a 2"-3” change of impact @ 25 yards.
Impact is low, raise rear sight.
Impact is high, lower rear sight.

*The exportation of tritium is tightly controlled and we cannot export any products containing tritium at this time.