Seiko 5 Sports Speed-Timer "UFO" 6138-0010 (1970)

Available now on auction by Second Vintage This is a highly collectible example of the iconic Seiko 6138-0010, widely known among collectors as the "UFO" due to its substantial, lug-less cushion case design. This specific piece is a Japanese Domestic Market (JDM) variant, distinguished by the "Speed-Timer" branding on the dial and the specific "5 Sports" logo. Notably, the caseback bears the "Waterproof" inscription rather than the later "Water Resistant," confirming this as a very early production model from the beginning of the 6138 lifecycle. It represents a significant piece of horological history from the golden era of Japanese automatic chronographs. Brand: Seiko Model: 5 Sports Speed-Timer "UFO" Chronograph Reference Number: 6138-0010 Serial Number: 025079 Movement: Automatic Caliber 6138 Dial: Black chronograph dial with champagne sub-registers Case Size: 44 mm (excluding the crown) Case Material: Stainless Steel Production Year: 1970 Condition: Good vintage condition (Timegrapher: -56s-62s/day. Which indicates the movement is functional and operational. Dial and Hands The watch features a matte black dial with the correct "Seiko 5 Sports Speed-Timer" nomenclature at the 9 o'clock position. The two vertical sub-registers are finished in a champagne gold tone which has developed significant, heavy patina and spotting consistent with age, giving the watch a rugged vintage character. The handset includes the original baton main hands and the distinct orange chronograph sweep hand and sub-dial hands. A day-date window is positioned at 3 o'clock, featuring an English day wheel. Case and Crystal The massive 44mm stainless steel cushion case presents in honest vintage condition, showing visible dings, scratches, and signs of use throughout. The case retains its distinctive saucer-like shape. The fixed bezel features a black tachymeter insert with red accents from 12 to 3 o'clock, which shows fading, scratches, and edge wear commensurate with the watch's age. The crystal is clear but may show minor handling marks. The caseback is the desirable screw-down type with the rare "Waterproof" stamping, confirming its early 1970 provenance. Movement Powering the watch is the legendary Seiko Caliber 6138A, a 21-jewel automatic chronograph movement. This movement is historically significant as one of the world's first automatic chronographs to feature a column wheel and vertical clutch, as well as the ability to be hand-wound. The movement is running and operational. Strap The watch is fitted with its original vintage stainless steel Seiko 5 Sports bracelet that complements the substantial case design perfectly. The clasp features the "5 Sports" branding. The bracelet fits a wrist size of approximately 18cm and shows stretch and wear consistent with the rest of the timepiece. Condition This timepiece is in fair vintage condition. It has been used and enjoyed, evidenced by the wear on the case, bezel, and the heavy oxidation spots on the sub-dials. The dial lume has aged to a dark tone. While the watch shows its fifty-plus years of history, it remains a complete and original example of a sought-after reference. Dimensions The case measures 44mm in diameter, giving it a commanding presence on the wrist that feels modern despite its vintage origin. Remarks The 6138-0010 is a pillar of vintage Seiko collecting. Finding an early "Waterproof" JDM Speed-Timer variant is becoming increasingly difficult. This watch offers a genuine, unrestored vintage aesthetic that appeals to collectors who value honesty and history over perfection. History Seiko released the 6138 caliber in 1970 as a follow-up to the groundbreaking 6139. Unlike its single-register predecessor, the 6138 offered a dual-register layout (12-hour and 30-minute counters) and hand-winding capability. The "UFO" helped define the chunky, adventurous aesthetic of 1970s sports watches and remains one of the most comfortable large chronographs to wear due to its hidden lugs. / Second Vintage SKU: SEI4YO6VB0000