IWC GST Aquatimer

Most IWC GST Aquatimer references take a 22 mm watch strap: 65 of 110. The lug width follows the case size: 40 mm case → 22 mm, 42 mm case → 20 mm, 43 mm case → 20 mm and 44 mm case → 22 mm.

Shop 20 mm Shop 21 mm Shop 22 mm

IWC GST Aquatimer lug width by case size

110 references measured. Updated 2026-10-29.

Case	Lug width	References	Watch strap attachment	For example
34 mm	20 mm · 21 mm on 1	3	—	IW3727-01, IW3727-02
38 mm	18 mm	1	—	IW812AD-01
40 mm	22 mm · 20 mm on 1	6	—	IW3707-01, IW3707-03, IW3707-06
42 mm	20 mm · 22 mm on 9 · 21 mm on 3	22	—	IW3288-01, IW3290-02, IW3290-03
43 mm	20 mm · 22 mm on 10 · 21 mm on 2	25	—	IW3756-03, IW3756-05, IW3756-06
44 mm	22 mm · 20 mm on 4	37	—	IW3410-01, IW3410-02, IW3568-01
45 mm	22 mm · 20 mm on 1	3	—	IW3580-02, IW3580-03
46 mm	22 mm · 20 mm on 2	6	—	IW3547-03, IW3557-01, IW3580-01
49 mm	20 mm · 22 mm on 2	6	—	IW3794-01, IW3794-02, IW3794-04
not recorded	20 mm	1	—	IW3795-02

References that take a different watch strap

IW3727-03: 21 mm, not the 20 mm of most 34 mm cases
IW3707-13: 20 mm, not the 22 mm of most 40 mm cases
IW3288-02: 22 mm, not the 20 mm of most 42 mm cases
IW3288-03: 22 mm, not the 20 mm of most 42 mm cases
IW3290-01: 21 mm, not the 20 mm of most 42 mm cases
IW3290-04: 22 mm, not the 20 mm of most 42 mm cases
IW3290-05: 21 mm, not the 20 mm of most 42 mm cases
IW3536-02: 22 mm, not the 20 mm of most 42 mm cases
IW3536-03: 21 mm, not the 20 mm of most 42 mm cases
IW3538-03: 22 mm, not the 20 mm of most 42 mm cases
IW3538-04: 22 mm, not the 20 mm of most 42 mm cases
IW3548-07: 22 mm, not the 20 mm of most 42 mm cases
IW3719-18: 22 mm, not the 20 mm of most 42 mm cases
IW3719-33: 22 mm, not the 20 mm of most 42 mm cases
IW3756-01: 22 mm, not the 20 mm of most 43 mm cases
IW3756-02: 22 mm, not the 20 mm of most 43 mm cases
IW3756-04: 22 mm, not the 20 mm of most 43 mm cases
IW3756-13: 21 mm, not the 20 mm of most 43 mm cases
IW3756-14: 21 mm, not the 20 mm of most 43 mm cases
IW3756-15: 22 mm, not the 20 mm of most 43 mm cases
IW3756-16: 22 mm, not the 20 mm of most 43 mm cases
IW3756-17: 22 mm, not the 20 mm of most 43 mm cases
IW3756-21: 22 mm, not the 20 mm of most 43 mm cases
IW3756-22: 22 mm, not the 20 mm of most 43 mm cases

And 11 more in the full list below.

Questions about the IWC GST Aquatimer

Do all IWC GST Aquatimer case sizes take the same watch strap?

No. The lug width changes with the case size: the 40 mm case takes 22 mm, the 42 mm case takes 20 mm, the 43 mm case takes 20 mm, the 44 mm case takes 22 mm and the 46 mm case takes 22 mm. Check your case diameter before you buy.