Key benefits Multilayer muscle sculpting with the triple spring resistance system enables progressive training adaptation and effective muscle activation to help define chest, shoulders, and arms. U shaped design fully engages the core while stimulating pectoral, shoulder, and thigh muscles, allowing wider motion paths for more advanced workouts. Reinforced spring rod structure and triple locking buckles prevent load displacement, providing joint protection and sustained durability during consistent use. Lightweight, folding construction offers portable convenience with effortless 3second quick disassembly and compatibility with standard storage bags for home or travel use. Core features Function: arm trainer designed to improve upper body strength and core engagement through layered resistance. Design: U shaped build to enhance core involvement and enable broader range of motion. Resistance and safety: triple spring resistance system paired with a reinforced spring rod and triple locking buckles to maintain stability and reduce movement. Portability: lightweight and foldable, disassembles in about 3 seconds and fits standard storage bags for easy transport and storage. Specifications and attributes Resistance system: triple spring Assembly: folding design with quick disassembly Construction: reinforced spring rod with triple locking buckles Compatibility: fits standard storage bags for home or travel use Performance: designed for consistent use with joint protection and durable operation Use scenarios Home workouts: integrate into upperbody routines to sculpt chest, shoulders, and core while progressively increasing resistance. Mixed training: pair with other equipment in fullbody circuits to activate chest, shoulders, core, and thighs with wider motion paths. Travel and small spaces: take on trips or in tight spaces; quick disassembly and compact storage without sacrificing functionality.