it means its set up for a firearm more or less .. that can be adjusted rather easily by loosening the inner ring on the end bell, they make a spanner tool for that if its tight .. google the method ..
$1k scope i bought for $500 . Ebay it was NIB sealed didnt mention it was70 yard minimum and once opened no returns , Great scope for long distance 8.5 x 25 x 50 . OK thanks