Here we have a March 1967 Seiko Monopusher Chronograph reference 5717-8990. 
The model was first produced in 1964 for the Tokyo Olympics. It has a well sized 37.5mm Stainless Steel case with the bi-directional rotating bezel surrounding the dial. The lugs have the tapered facetted design, with the flat sides to the case. The stop seconds pusher is at 2 O’clock, with the chunky crown below. It has the original domed crystal, with a silver sunburst dial having applied baton hour markers and date window at 3 O’clock. It is surrounded by a dark grey seconds track. The silver sword hands indicate the time. To the rear is the snap on case back with the Seiko Seahorse to the centre. Inside is the Seiko calibre 5717. It is a manual wind chronograph movement, which is functioning perfectly and keeping reliable time within +20 seconds a day. It is an unpolished example, with the case back engraving remaining good and clear. 
 
The bezel is an enjoyable aspect of the watch, with the primary purpose being to count the minutes you are timing. Set the triangle on the minute hand when you start the chronograph and read the minutes from the bezel when you stop it. 
 
The dial is such a clean design, managing to incorporate the time, date and chronograph function. The silver sunburst finish is bright and clear, with the dark grey seconds chapter ring providing the perfect break before the silver tone bezel. The baton hour markers are impactful, with the three-dimensional applied design. They have a polished outer section, with the frosted main face which changes the way they reflect the light, contributing further to their impact. The design is balanced with the date window at 3, with the applied frame surrounding it. The hour and minute hands are sharp, of sword shape, with no counterbalances. The second hand is thin and sharp, which compliments the sleek design of the chronograph function giving an accurate, pinpoint feel. The use of texture is perfectly rounded off with the applied Seiko logo below 12. 
 
The calibre 5717 is manually wound, with a jewel count of 21. It operates at a frequency of 18,000 BPH, with horizontal coupling and a column wheel which controls the single pusher that stops, starts and resets the seconds. 
 
In 1964 a home Olympics provided Suwa Seikosha with the perfect opportunity to develop their first chronograph wristwatch. This was a statement of intent from the company, being able to provide such a timing device for the event. The model is known as the ‘Seiko Chronostop’ due to the similarity in use and function to the Omega Chronostop. 
 
Full condition report below. Please see the images as these compliment and aid the description provided below.
 
Dial: 
The dial is original and is in good condition for the age. The silver tone is good and bright, as are the hour markers. There is no discolouration. There are some small areas of ageing to the lacquer near 9 O’clock, with one or two small marks to the finish.
 
Hands: 
The hands are original and are in good condition with the silver shine. They have no obvious marking.
 
Glass: 
The acrylic crystal is original and is in decent condition. It has some marking with some nicks to the edges. 
 
Pusher:
The pusher is original and unpolished, with light marking associated with age. It functions well.
 
Crown: 
The crown is original and unpolished. It in decent condition with some light marking.
 
Bezel:
The bezel is formed of Stainless Steel and is in decent, unpolished condition. It has a brushed finish with marking associated with age. It has some noticeable scratching and nicks. It still has the black in-fill to the text, but the triangle at 12 has lost it.
 
Case:
The case is formed of Stainless Steel and is in decent, unpolished condition. It has light scratching and nicks associated with age.  
 
Caseback:
The case back is stainless steel and is in good condition with polished finish to the face and the brushed finish to the outside. It has light surface scratching associated with age. The seahorse motif is good and clear, as well as the serial number and reference signing. There are some scratches to the edges from opening. It remains unpolished.
 
Strap: 
The watch comes on a tan leather racing style strap, which is non original. 
 
Movement: 
The movement is a Seiko calibre 5717, which manually wound with a jewel count of 21. It operates at a frequency of 18,000 BPH, with horizontal coupling and a column wheel which controls the single pusher that stops, starts and resets the seconds. The date has a quickset function too. 
 
The movement service history is unknown, but it is in good condition. It’s keeping time to within +20 seconds deviation a day, with an amplitude of 310 degrees and a beat error of 0.5m/s.
 
Case dimensions: 
Case width: 37.5mm
Case width with crown: 40.75mm 
Case length: 37.5mm 
Case length lug to lug: 45mm
Case Depth: 11.5mm
Lug width: 18mm