so it's just due to different manufacturing years

Waist Size: 29" / X Small Slim - Label states "Waist 76cm"

Waist Size: 39" | Suggested Size: Large Regular - Label suggests a waist from 104 - 108cm

but the previous owner has removed these

Czechoslovak Army M85 Faux Fur Trouser Liners - W40 L30 DPM so it's just due toAt a glance Faux Fur Material Drawstring Waistband Button Fly Elasticated Cuffs Warm & Comfortable Works as loungewear Cold War Warsaw Pact Eastern Bloc Kit Grey Colour Waistband Flat: 20" Suggested Size: Large Regular Inside Leg: 30" Regular Total Length: 40" Vintage Militaria Issued 1980's Genuine Czechoslovak People's Army SLA Surplus Grades Grade 1 Great condition, some prior use, may benefit from a wash with fabric conditioner but still in lovely