Click to expand Tap to zoom KWA RM4 ERG Charging Handle Spring Retainer by KWA Save Liquid error (snippets/product-badge line 32): Computation results in '-Infinity'% $17.99 SKU 199-1601-M324 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Add to cart This polymer spring retainer fits all RM4 ERGs and appears on diagrams as mechbox part 324. Part 199-1601-M324