There are aparently at least 2 versions of this lens, an older T-mount version which is quite larger and heavy and a T4/TX version of the lens which is extremely compact and light. I was lucky enough to get the T4/TX version of the lens.
The lens takes a 58mm filter, is 6″ in overall length and it weighs something a bit less then my 70-210mm vivitar series 1 lens, maybe 1lb 4oz-1lb 6oz (I’ll update the weight when I actually measure it). The f/5.6 maximum aperature makes it a fairly dim lens, especially when trying to focus in heavy overcast or near dusk/dawn, however it is sufficient to focus into shade (so long as it is not deep shadow) and for daylight use on anything other then a stormy day. The maximum aperature of the lens is f/22 with a minimum focusing distance of about 17.5ft.
The lens appears to be multicoated, but there is no indicator that is or not. I am basing it solely off how the front element is reflecting light. According to the serial number the lens was actually manufactured by Tokina for Vivitar. The lens also has a built in extendable lens hood.
The lens is fairly sharp, especially when stopped down a couple of stops. Both photos below were taken on a sunny day using iso400 film at 1/1000s, f/11 and handheld and are quite sharp. This is quite a nice lens for daylight telephoto shooting.
One of the downsides of this lens is that it does not have a tripod collar. It is quite small and light enough to be used handheld without to many problems, but with a 300mm focal length it can be hard to hold steady and I don’t think I would be able to manage 1/250s shutter speed without bracing myself some or using a beanbag or tripod (where the tripod collar would be nice, though the lens is light enough it doesn’t really need one). However, at 1/500s or 1/1000s it should be just fine.
I actually managed to find this lens on Craigslist and it is in excellent condition.
Here is another picture for size comparison of the 300mm large