Use the Swarovski Optik 1.7x Magnification Extender to increase the magnification of your ATX, STX, or BTX family of modular spotting scope systems without affecting the functionality in any way. This accessory simply installs with a simple twist between the objective and eyepiece modules using a simple bayonet mount. The ME 1.7x magnification extender increases the magnification by a factor of 1.7. You can quickly and easily attach it using the bayonet catch to all the objective and eyepiece modules in the ATX / STX / BTX family. In the case of the BTX 65 and 85, the magnification increases from 30x to 50x, and from 35x to 60x for the BTX 95 and 115.