Normally charging and discharging300-500 times, after 300 times, it starts to decay to 80% capacity, which is manifested in rapid power failure. 

It can be used for up to 80 hours with the charging compartment, and the battery life of the headset can be up to 4 hours. 

1.1/2 is stronger, the transmittance in the visible light range of 1/2 is T=80, and 1/4 is T=84 

Yes. I have the same lens and adaptor on my Sony a7ll and it works beautifully. The m42 is also known as the 'universal' mount as other 3rd party camera and lenses also used it. I own 6 other K&F e-mount adaptors to different lens makers (ltm, MD, CF/CD, Nikon) and they all are well built with a nice snug fit. Highly recommended. 

I actually have not received this adapter yet. It's shipping from China. Don't think that was disclosed in the ad. However, I do not believe this is for the Pentax Q body rather for digital and film cameras that take the Pentax K mount in its many variations. So I'm expecting to be able to mount my Leica M mount lenses on my digital and film Pentax K mount cameras, no autofocus or relay of exposure information, only to be used with manual focus and exposure.