BG549807358 Equivalent other manufacturer (OEM).

BG549807358 Description says 300 DPI. I've ordered one and will report back.

BG549807358 Yes.

BG549807358 Yes it does. I have the exact same shaver myself. The only thing I noticed is that the horizontal switch on the front of your shaver will not stop the foils from pivoting. It appears to lack the locking mechanism. An insignificant point in my experience. One other thing you may wish to know is that if your old foil has a silver metal bezel, it is quite easy to carefully take the foil unit out using a flat headed screwdriver and replace it with the new one. It's just a case of two plastic catches. This will give you a new foil but will enable you to keep the more durable metal casing so you can keep 'tapping out' your shavings after each shave ;o)

BG549807358 This model would be more than suitable. x1200 (if true) is just silly magnification -- that's the sort of mag. you would look for if you were interested in observing blood cells etc. For the purposes you have outlined, and the fact that your child is only 7 y.o. this is going to do more than they require. On a side note, keep the box. You can turn the monitor sideways (inline with the stand), roll it down to its lowest position and fit it neatly and safely in there ;o) Also, I would stick a piece of black card or foam to the base to provide a bit of contrast against your samples. Hope that helps.

BG549807358 Chinglish at its best, I know. long story short having got a couple of these myself, a single 18650 cell will do very well. You'll get very loud ~20mm arcs. With a bench power supply taken up to 6V I didn't really see much of an improvement though there was a small one. I'd say play it safe -- go middle of the field with voltage. Use a single 18650 cell. Just remember that you can't drive it for more than a handful of seconds at a time.

BG549807358 Buy one!