Kowa's TE-9Z 20-60x Zoom Eyepiece is compatible with the TSN-660, 600, and 82SV series of spotting scopes. The eyepiece attaches easily via the bayonet mount. The TE-9Z has 16/16.5 eye relief making it comfortable to use even with eye wear. Field of view with the 660 and 600 series scopes is 100 - 53 ft and 95-50 ft with the 82SV.