The Nebula

From Arnold & Son -

Courtesy of Arnold & Son

Available in Red Gold (18K), measuring 41.50 mm in diameter, 8.73 mm in height.

Courtesy of Arnold & Son

The movement is the A&S5101 it is fully skeletonized and symmetrical.  It is hand-winding, with two mainspring barrels, and a power reserve of 90 hours. 

It is also available in stainless steel -

Courtesy of Arnold & Son

Here are the pertinents -

Main technical characteristics: 

Calibre: 

A&S5101
Manufacture Arnold & Son calibre, fully skeletonized and symmetrical, hand-wound, 24 jewels, diameter 31.50 mm, two mainspring barrels, screwed balance wheel, thickness 4.04 mm, power reserve 90 h, 3 Hz / 21,600 vph, adjusted to 5 positions 

Functions:

Hours, minutes, small seconds 

Movement decoration: 

NAC-treated bridges and black ADLC-treated main plate (stainless steel model) or palladium-treated bridges and NAC-treated main plate (red gold model) with haute horlogerie finishing, chamfered bridges with polished edges and brushed surfaces, chamfered wheels with A&S three-spoke design and polished edges, gold chatons, screws with bevelled and mirror-polished heads 

Dial: 

Anthracite-coloured (stainless steel model) or light grey (red gold model) chapter ring 

Case: 

Stainless steel or 18-karat red gold (5N), 41.50 mm diameter, 8.73 mm height, cambered sapphire crystal with anti-reflective coating on both sides, sapphire crystal display case back, water resistant 30 m /100 ft 

Strap: 

Hand-aged anthracite calf leather (stainless steel model), hand- stitched brown or black alligator leather (red gold model) 

References: 

Ref. 1NEAS.B01A.D134A (stainless steel) 
Ref. 1NEAR.S01A.D135A (red gold)