The Televue Plossl (and widefield) eyepieces were early entries of Al Nagler into the prime eyepiece market (in 1980), and the Plossls are still one of the popular (and more affordable) Televue product lines. These Plossls have a 50-degree apparent field-of-view (FOV), which is quite respectable for relatively low-cost eyepieces (they sell new for $80-110 each). They come in a full range of focal lengths - from 55 mm (not shown in the above picture) to the more standard 40 mm, 32 mm, 25 mm, 15 mm, 11 mm, and 8 mm. For a long focal-length scope like my 12" LX200 (3200mm FL), they give a range of magnification from 80-400 power.

Note that the maximum power which can be used with a scope depends on the atmospheric conditions; a rule-of-thumb is that the maximum useable power of a scope is about 50 times the aperture in inches. Therefore, for a 4-inch scope, the maximum power should be about 200, while for a 12" scope, the power can reach 600 - theoretically ... but practically, powers above 200-300 are very seldom used. In fact, the current trend in astro-imaging is to show widefield views - i.e., corresponding to lower powers.