Three different buckles have been used on the side straps of the 3G AK models. All are for 15mm webbing.
Thety are best identified by the period of manufacture, and by looking closely at the images

Duraflex X-lite
This buckle is on all AK27, AK37, AK37-X, AK47, AK47-X, AK57 and AK70 rucksacks made before 2022. Later models have the Duraflex SJ Chromeo buckle.

Duraflex SJ Chromeo
This buckle is on all AK27, AK37, AK37-X, AK47, AK47-X, AK57 and AK70 rucksacks made after 2022. Earlier models have the Duraflex X-lite buckle.

Duraflex Mojave buckle
This buckle is on AK37.AK37-X/AK47/AK47-X rucksacks made in 2022 from the Indonesia factory only.