Like all Ethos eyepieces, it has a comfortable view with 15 mm pupil distance (focal length).

Although the eyepiece is a good 15 cm high, it weighs a comparatively modest 500 g. Due to its slim design (56 mm diameter), the 3.7 mm Ethos-SX is binocular compatible.

In contrast to the other Ethos eyepieces, the Ethos-SX 3.7 mm is not a hybrid with integrated 1.25 inch and 2 inch receptacle, it only has a 1.25 inch eyepiece connector. However, an adapter is supplied with the eyepiece, which extends the plug-in size to 2 inches. This means that the Ethos-SX 3.7 mm can also be used with the plug-in size that allows the easiest handling in practice. With the 1.25 inch connection you can achieve an approximate parfocality with the TeleVue Plössl, Panoptic, Radian, Nagler, Ethos 6 mm and Ethos 8 mm. With the 2 inch connection the Ethos-SX is 3.7 mm parfocal with the Ethos 13 mm and 10 mm.