The 
Double Bell AM45 Detonics GBB airsoft pistol is a compact, full-metal gas blowback airsoft pistol known for its realistic feel and Tokyo Marui-compatible internals.
Specifications and Features
Construction: Features a durable full metal slide and frame, with some polymer components for the grip panels and a high-density polymer compensator on some variants.
Power Source: Uses green gas to power its realistic blowback action.
Muzzle Velocity (FPS): Fires at approximately 251–310 FPS (feet per second) with 0.20g BBs, making it suitable for CQB (Close Quarters Battle) scenarios.
Hop-Up: Includes an adjustable hop-up mechanism to fine-tune shot accuracy.
Magazine Capacity: Typically comes with a 15-round gas magazine (for the M199/797B variant) or an 18-round magazine (for the "Vorpal Bunny" variant).
Design: Inspired by the classic 1911 design, with several models featuring a modern, distinctive front compensator. The "Chisato" variant is a replica of the pistol carried by the character Chisato Nishikigi in the anime TV series Lycoris Recoil.
Compatibility: The internals are based on the Tokyo Marui spec, allowing for easy upgrades of parts like the hop-up rubber and inner barrel. 
User and Expert Opinions
Realism and Feel: Reviewers and retailers consistently note the realistic kickback effect due to the gas blowback system and the authentic feel provided by the full-metal construction.
Durability: The robust metal build ensures longevity and performance on the field.
Aesthetics: The modern front compensator is a major aesthetic highlight, appealing to those seeking a unique-looking sidearm or fans of the Lycoris Recoil anime.
Performance: While praised for its performance as a compact sidearm, some experts note that the small gas reservoir in the magazine means it might not be a primary performance choice compared to larger pistols like a Hi-Capa, but it perfectly fulfills its role as an authentic replica.