Not worth a lot, but at least you now have the correct Walther LGR set from Bob. Air arms and cheapo sights are really not worth the effort, they look like sights, but there it ends!
The ten metre rifle ten dot is 0.5 mm, the backlash and slack on the cheap sights produce an inaccuracy several times over that, you get what you pay for with sights.

The original LGR and LGV sight although a course adjustment by modern standards are a very good and tight sight, I have a couple I use on rifles for small juniors, as they are short and let a shorter person do an over the sight pre zero check, where some of the modern ones are too tall for that. The modern trend is towards smaller sights which aids pre sighting, and also aids balance, as there is a wider view, but you are now looking closer to upwards of £400 for a top spec modern sight, although I strongly favour the Gehmann compact at £140 ish as the best buy value for money. We've used those for everything, and my wife currently has one on her 300 metre Keppeler.

Have Fun
Robin