I use a pen light to candle. You can't see much at all but you can tell if there is development. I haven't been able to see movement but have been able to distinguish between the air sac and the chick and have been able to see veins but just barely. Anything after that and its just too tiny to tell. I've been wondering about this candler and if it would work. A little out of my price range tho for a candler.....
A good temporary one is to take a shoe box and cut a hole in the bottom 1/4 the size of the egg you want to candle.In a dark room lay the egg over the hole and then hold the box over a 75watt light bulb. more permanent one ....build a box out of wood that is about 5"x5" square and about 10" tall with a bottom on it.Drill a hole 1/4 the size of the egg ya wanna candle and set the box over an el cheapo light fixture mounted to a board with a 75 watt bulb in it. You can have different tops for it with different size holes to accomodate various eggs.
Yes I recommend the Brinsea Hi density cool egg lume candler - for all dark eggs, hens, bantams, all equally well seen for button (aka King ) quails also. When alive and moving you see them move, also the beak as it is protuding through the air sac. Remember do not open you incubator more than necessary, candle as seldom as necessary.
It is available in both 220 volt (our country) also 110 volt (USA)