Usually this is known as a FRAG POUCH. 

Key Features are -

• Quick release clip (ITW Gillotex IR)
• Velcro Top Cover
• Internal Fly off leaver loop
• Double and Triple stitching with half pouch zip
• Designed to fit the latest L109
• On the rear side it has Molle attachment system. 
• Most grenade will fit this Pouch. 
• Made in Great Britain
• Has Odin Lifetime Warranty

Material used is 500D cordura fabric (abrasion resistant)