The 551 advanced dot sight from Strike Systems is well built from metal and hard plastic.
It features rear-facing buttons.
For example, you can have a button for turning on / off and buttons for changing the color of the crosshairs, red or green
You can also adjust the brightness of the reticle.
Fully adjustable height and wind correction.
The two LR44 batteries are stored in an easily accessible area.
This is equipped with a kind of lever,
so you can quickly and easily change your batteries if necessary.
The mounting has a simple screw locking system with which you can quickly mount it on a Picatinny or weaver rails.