So, Despite being a 42mm adapter, this will not work with your M42 lenses. i tried.The threads on the 42mm side do not match the threads on a M42 lens.Other than that, the adapter seems to be well made, and attractive in its black coating.I purchased because the 42mm side is adjustable to place lens control indicators in a convenient position so you don't have to preset or get down underneath the lens to see the settings.

Nicely finished; fits on a Pentax K20D; screws onto standard astrophotography adapter. I am happy.

Item is exactly as advertised: High quality metal and it fits my Pentax like a glove! This simple inexpensive item opens up an whole new world of photography for either digital or traditional film! Get it on Amazon! You will wonder why you did not do it sooner.

Very simple device for a very basic purpose and it works just fine. The K mount attachs to my new Pentax KP perfectly and I tried it on some old legacy Pentax bodies (K1000 and a Super Program from the film days) just to see if the K mount had changed over the past 40 years. Fits well on everything. its tight enough to hold without any play but smooth enough to release when you want to remove it. The "click lock" grabs and locks the adapter in place just like it should.The T-mount threads work perfectly and very smoothly with an Orion 2" prime focus camera adapter so the T-threads appear to be properly machined. At this price point, this adapter is a real gem. I've become accustomed to paying for overpriced adapters. It was a was a very refreshing experience to find a capable adapter at a reasonable price.If I want to nitpick, the only tiny detail that could be improved is the size of the mount alignment marking. Most of my other stuff has either a big orange or white dot that is used to line-up the bayonet mount withe the camera. This unit has a very small indent and marking. Its obvious if I put my glasses on but could be enlarged for quicker referencing.Very nice overall.

Works and fits perfectly my Pentax K-50. No instructions within, but you must tighten the small screws with a jewelry scredriver to get attched to the scope camera adapter. I recommend to this indoors and with good light, so do it before going outdoors. This also means that once is tighten, you will almost have the scope adapter fixed for this. I took great moon pics with my Meade 20-60x 80 mm spotting scope. For this price you won't get better solution.