Seiko SKX and Seiko 5 as mod bases
A donor watch is an existing watch used as the starting point for a mod. These guides help you identify the reference, check its dimensions and plan changes. MedoMods builds and sells finished mods with their own specifications, also shown here as style alternatives.
Seiko SKX007
Use the SKX007 as a reference page for dimensions, calibre marking and parts compatibility. Check the exact watch and its fitted components before planning changes.
Learn more →Seiko SKX009
Plan an SKX009 mod around the dial, hands and bezel colour scheme. Check the exact reference and fitted components before choosing replacement parts.
Learn more →Seiko SKX013
For an SKX013 mod, check the case dimensions, wrist fit and reference-specific parts. Compare the dial, hands, crystal and bezel before planning changes.
Learn more →Seiko 5 Sports SRPD (5KX)
Seiko specifies SRPD51 with calibre 4R36, a 42.5 mm stainless steel case, 22 mm lug width, Hardlex crystal and 10 bar water resistance. Check each SRPD reference separately.
Learn more →Seiko 5
Seiko 5 covers different references and case styles. For example, Seiko specifies SRPD51 and SRPK89 with calibre 4R36; use the exact model specification to plan your mod.
Learn more →Seiko Turtle (SRP777)
Seiko specifies the SRP777 with a 45 mm stainless steel case, calibre 4R36, a Hardlex crystal and a 200 m water-resistance rating.
Learn more →Seiko King Turtle (SRPE05)
For the SRPE05, Seiko lists a 45 mm stainless steel case, calibre 4R36, a sapphire crystal, a ceramic bezel and a 200 m water-resistance rating.
Learn more →Seiko Willard (SPB151 / 6105)
Seiko presents the SPB151 as a modern reinterpretation of a 1970 diver with an asymmetric case design.
Learn more →Seiko Monster (SRP / SKX779)
Seiko documents the SRPD25 with a 42.4 mm stainless steel case, calibre 4R36, a Hardlex crystal and a 200 m water-resistance rating.
Learn more →Seiko SPB143 (62MAS)
Seiko documents the SPB143J1 with a 40.5 mm stainless steel case, calibre 6R35, a sapphire crystal and a 200 m water-resistance rating.
Learn more →Seiko 5 Sports GMT (SSK)
Seiko specifies SSK001 with calibre 4R34, a 24-hour hand and date display, a 42.5 mm stainless steel case, Hardlex crystal and 10 bar water resistance.
Learn more →Seiko Samurai (SRPB/SRPF)
For the Samurai example reference SRPB51, Seiko lists calibre 4R35, a Hardlex crystal and a 200 m water-resistance rating.
Learn more →Seiko Alpinist (SARB017 / SPB)
Seiko lists the SPB121J1 with the 6R35 calibre, a 39.5 mm case, sapphire crystal and 20 bar water resistance.
Learn more →SKX007, SKX009 and SKX013: choose the exact reference
Start with the model reference and the components already fitted. Compare the case diameter, height, lug-to-lug length and lug width, then the dial, crystal, bezel and movement. The individual SKX guides cover the checks to make before planning a build.
Seiko 5 Sports SRPD: a documented example
Seiko specifies SRPD51 with calibre 4R36, day/date, hand winding and stop seconds. Its stainless steel case measures 42.5 mm in diameter, with 22 mm lug width, Hardlex crystal and 10 bar water resistance. These figures describe SRPD51 as supplied by Seiko, not every Seiko 5 or a finished mod.
Other Seiko families as design references
Turtle, King Turtle, Monster and Samurai guides focus on their respective references. Alpinist, SPB143 and Willard have separate guides too. Use those references to choose the look and check the actual parts; a family name alone does not establish compatibility.
Donor watch questions
- Which measurements matter when choosing a donor watch?
- Check case diameter and height, lug-to-lug length and lug width. For replacement components, also compare the dial, hands, crystal, bezel, movement holder and crown stem with the exact reference.
- Do all Seiko 5 watches use the same movement?
- No. Check the specification for the exact reference. For example, Seiko specifies calibre 4R36 for SRPD51 and SRPK89; this is not a movement claim for the entire Seiko 5 family.
- Are the linked MedoMods watches built from these original Seiko models?
- The links show finished MedoMods models with their own specifications, chosen for their style. They do not state that an original Seiko donor was used.