Angled Eyepiece
A spotting-scope eyepiece set at an angle to the body, letting a shooter view comfortably from prone or a seated position behind a tripod.
An angled eyepiece sits at roughly forty-five degrees to the main tube of the spotting scope, so the viewer looks down into it rather than straight through. From prone or a low seated position this is far more comfortable than a straight eyepiece, because the head stays relaxed and the neck does not crane to find the view. It also lets a shooter keep the tripod low and stable while still seeing the image clearly.
The angled design shines when a team shares one optic, since two people of different heights can both reach the eyepiece without moving the tripod head. It also helps when glassing uphill at steep targets, where a straight tube would force an awkward posture. The tradeoff is that a straight eyepiece can be quicker to point at a target you found with the naked eye, so the choice depends on how the glassing is done and at what magnification the work happens.