20 grams of C4 or similar plastic explosive would be more than adequate to produce the effects seen. CL-20 wouldn't be a good choice for this deployment: it's not particularly stable for rough handling even with a good phlegmatizing blend, and tends to decompose at the temps one would expect a pager to be exposed to (hot car, etc).

That's a fair point my knowledge of explosive chemicals only stems from conventional missile-based warheads and propellants. It's very possible a different explosive was used.

C4 would be easily detectable by spectrometers, including at the airports, wouldn’t it?

per a calculator on unsaferguard.org 20g of RDX

Injury/Fatality to Personnel Range (m) Fatal Distance 0.64 Lung Damage 1.02 Eardrum Rupture 2.63

So apparently, it must be less than 20 g of RDX, and/or a weaker explosive: if the fatal distance was within 0.64 meters, there would be significantly more reported deaths.

Or: lower-abdominal proximity has lower lethality.

That charge, held to the ear, would have had a considerably stronger effect.

Distance in meters?

NB: add two spaces before text for "code" formatting, or two linebreaks between lines.

  Injury/Fatality to Personnel Range (m)
  Fatal Distance 0.64
  Lung Damage 1.02
  Eardrum Rupture 2.63

(I'd found your comment in an Algolia search result which shows your original linebreak as entered.)

The word on X is it was Pentaerythritol Tetranitrate (PETN): https://x.com/MattWGraver/status/1836093195240800522 (not me)