Longines Master Collection

Most Longines Master Collection references take a 21 mm watch strap: 163 of 452. The lug width follows the case size: 39 mm case → 20 mm, 40 mm case → 21 mm, 42 mm case → 21 mm and 44 mm case → 20 mm.

Shop 18 mm Shop 20 mm

Longines Master Collection lug width by case size

452 references measured. Updated 2026-10-29.

Case	Lug width	References	Watch strap attachment	For example
26 mm	13 mm	30	—	L2.128.0.87.3, L2.128.0.87.6, L2.128.4.51.3
29 mm	15 mm	27	—	L2.257.0.87.2, L2.257.0.87.6, L2.257.4.51.6
34 mm	18 mm	34	—	L2.357.0.70.2, L2.357.0.73.2, L2.357.0.73.6
36 mm	19 mm · 20 mm on 12	33	—	L2.518.0.87.6, L2.518.4.51.3, L2.518.4.51.6
39 mm	20 mm	68	—	L2.628.4.51.5, L2.628.4.51.6, L2.628.4.51.7
40 mm	21 mm · 20 mm on 11 · 18 mm on 1	106	—	L2.622.4.71.1, L2.629.4.92.0, L2.673.4.51.5
41 mm	20 mm	16	—	L2.714.4.71.3, L2.714.4.71.6, L2.714.4.78.5
42 mm	21 mm · 20 mm on 20	89	—	L2.665.4.51.5, L2.665.4.51.6, L2.665.4.51.7
44 mm	20 mm · 22 mm on 18	38	—	L2.693.4.51.5, L2.693.4.51.6, L2.693.4.51.7
48 mm	25 mm	11	—	L2.640.4.51.5, L2.640.4.78.3, L2.640.4.78.5

References that take a different watch strap

L2.503.0.03.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.03.6: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.07.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.07.6: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.83.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.83.6: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.87.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.87.6: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.93.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.93.6: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.97.3: 20 mm, not the 19 mm of most 36 mm cases
L2.503.0.97.6: 20 mm, not the 19 mm of most 36 mm cases
L2.629.4.51.5: 20 mm, not the 21 mm of most 40 mm cases
L2.629.4.51.6: 20 mm, not the 21 mm of most 40 mm cases
L2.629.4.51.7: 20 mm, not the 21 mm of most 40 mm cases
L2.629.4.78.3: 20 mm, not the 21 mm of most 40 mm cases
L2.629.4.78.6: 20 mm, not the 21 mm of most 40 mm cases
L2.629.4.92.6: 18 mm, not the 21 mm of most 40 mm cases
L2.648.4.51.5: 20 mm, not the 21 mm of most 40 mm cases
L2.648.4.51.6: 20 mm, not the 21 mm of most 40 mm cases
L2.648.4.51.7: 20 mm, not the 21 mm of most 40 mm cases
L2.648.4.78.3: 20 mm, not the 21 mm of most 40 mm cases
L2.648.4.78.6: 20 mm, not the 21 mm of most 40 mm cases
L2.692.4.51.7: 20 mm, not the 21 mm of most 40 mm cases

And 38 more in the full list below.

Questions about the Longines Master Collection

Do all Longines Master Collection case sizes take the same watch strap?

No. The lug width changes with the case size: the 34 mm case takes 18 mm, the 39 mm case takes 20 mm, the 40 mm case takes 21 mm, the 42 mm case takes 21 mm and the 44 mm case takes 20 mm. Check your case diameter before you buy.

Can two Longines Master Collection watches with a 40 mm case take different watch straps?

Yes. Of the 106 Longines Master Collection references with a 40 mm case, 94 take 21 mm, 11 take 20 mm and 1 take 18 mm. The reference number decides, not the case size alone.