DuFrane · Microbrand · United States
DuFrane Bergstrom MkIV
- Sellita SW261-1 M
- 41.5 mm × 12.6 mm
- Sapphire crystal
- 50 m water resistance
Where to buy
- DuFraneUS
Movement
- Caliber
- Sellita SW261-1 M
- Type
- Hand-wound
- Tier
- Upper
- Complications
- Small seconds, Date
- Frequency
- 28,800 bph
- Power reserve
- 42 h
- Hacking
- Yes
- Accuracy (factory)
- —
- Grade
- Elaboré
- Brand regulation
- -4 / +4 s/day
- Modifications
- Decorated with Geneva stripes and blued screws
Case
- Diameter
- 41.5 mm
- Lug to lug
- 50 mm
- Thickness
- 12.6 mm
- Lug width
- 22 mm
- Material
- Steel (316L)
- Hardening
- —
- Water resistance
- 50 m
- Crown
- Screw-down
- Case back
- Display, screw-down
- Bezel
- —
- Finishing
- Polished
Crystal & dial
- Crystal
- Sapphire
- Shape
- Double-domed
- Anti-reflective
- Yes (side not stated)
- Lume
- Super-LumiNova C3
Bracelet & clasp
- Style
- Mesh
- Links per row
- —
- Solid end links
- —
- Solid links
- —
- Link attachment
- —
- Taper
- —
- Quick release
- —
- Half links
- —
- Clasp
- —
- Micro-adjust
- Tool-free, "Sliding buckle"
- Diver extension
- —
Straps
- Strap 1
- Leather, Epsom leather strap, included with the mesh bracelet
Weight
- Head only
- —
- On bracelet
- —
- On strap
- 65 g
Prices
Variants
| Name | Dial | Configuration |
|---|---|---|
| Black Horizon | Black | polished steel case |
| Blue Horizon | Blue | polished steel case |
| Black PVD Black Horizon | Black | polished black PVD case |
| Black PVD Blue Horizon | Blue | polished black PVD case |
About this entry
79% of key specs known. Missing: hardening, bracelet links, end links, link attachment.
Fourth version of DuFrane's original 2016 pilot model; earlier Bergstroms used the ETA 6498 (the importer had matched that caliber from the description's history line). The MkIV uses a hand-wound Sellita "SW261-M" (recorded as the SW261-1 M), elaboré grade, decorated with Geneva stripes and blue screws, regulated in Austin to +/-4 s/day; it adds a framed date window at 3 to the small seconds at 6 (photos). DuFrane quotes 48h of reserve; the factory figure recorded on the movement is 42h. Brand dimensions: 41.5mm, 50mm lug to lug, "11mm case thickness (12.6mm w/crystal)" (12.6mm recorded), 22mm lugs, 65g with the leather strap. Double-domed sapphire with "2x" AR coating (side not stated); screw-down sapphire display caseback. Numbered batch of 300, of which only 50 are in polished black PVD (across both dials); the black PVD finish is cosmetic colour, not a stated hardening. Ships on a polished mesh bracelet with a sliding buckle (recorded as tool-free adjustment) plus an Epsom leather strap. Release year from the listing's March 2024 publication and Master Horologer's April 2024 article.
Last verified: 2026-10-25. Edit or correct this entry.
Sources
- DuFrane Bergstrom MkIV (product page, specifications) accessed 2026-10-25
- Master Horologer, DuFrane Bergstrom MkIV (April 2024) accessed 2026-10-25