The majority of crossbow scopes that are variable power need to be locked in (no more power adjustment) when you determine speed and arrow weight. I have a discontinued Zeiss crossbow scope like this and its good. Also have the top line Hawke crossbow scope. I purchased the Sig Sauer SIERRA3BDX 2.5-8x32mm and really like it. You can adjust the power up or down and still use the 20,30 40 etc.
