Here we go. A bit of digging and the relationship to pitch and the numbering system becomes clearer. The 1.5 and 2 that prefix this type of belt are a multiplier of Pi. So in the case of 1.5 belts the pitch is actually 1.5 x 3.142 or 4.713mm, belts prefixed with a 2 like the one on my X3 are 2 x 3.142 or 6.284mm pitch.
If brian is able to give an idea of pitch then it should not be too hard to work out if he needs something like a 1.5×116 or 2x 87
Page 16 of this pdf catalogue is what enlightened me to the meaning of pitch. A search for "Module" belts may be worth trying.
Edited By JasonB on 07/01/2021 16:37:27