Brand: Gruen

Model: Precision Day-Nite "Jump" Dial ref. 510 Rss CA (RARE); Swiss Made circa 1960s

Case: Chrome-plated case with stainless steel screw-down caseback is approximately 34mm excluding the original unsigned winding crown

Strap: Vintage new old stock 11/16" (~18mm) black strap with stainless steel tang buckle

Movement: Gruen cal. N510CA manual-winding movement (17 jewels) with original dust cover; specially modified for day and night "jumping" function; 18,000 BPH; Swiss Made

Features: Stunning original silver sunburst dial with open aperture hour markers to accommodate the unique day and night "jumping" feature; a colored disc flips underneath the dial from black during daytime hours (6 AM - 6 PM) to fluorescent "nite-glo" green during nighttime hours (6 PM - 6 AM); original luminous hands; original center sweeping-seconds hand; 34mm case with domed acrylic crystal

Condition: Fantastic original condition overall with only light signs of wear consistent with age; 34mm case is completely unpolished with sharp edges/bevels and no visible wear through the chrome plating; crisp stainless steel screw-down caseback remains clearly legible with the original finishes in tact and a few minor toolmarks; incredible original silver sunburst dial; original luminous hands with a tiny bit of lume missing from the minute hand (hardly noticeable); clean domed acrylic crystal

Other: Looking for a unique conversation piece? Look no further than this rare and innovative Gruen Day-Nite. Gruen was way ahead of the times when they released this complication way back in the 1960s and it still doesn't get much cooler than this today... All Day-Nite models are rare, but try finding one in this condition. This particular example appears to have been worn sparingly. It slides nicely under the cuff of a dress shirt, but can also be worn effortlessly with a t-shirt and jeans - Show off those fluorescent mint green hour markers!