Fits directly over WEIHRAUCH (HW) Guides! Drop-in, Replacement size OEM Spring maximum power. Nicely fits the following HW/Beeman and Clone airgun guides for OEM+ power: R9/95, R10/85, R11 Size: 810 (20.5mm) x .125w (3.2mm) x 33 coils, closed/ground/polished Note: May fit other like size airgun guides