Amazon.com: Canvas Quick Release for Compatible G-SHOCK Watch | 100% Cotton Crafted Canvas | Black PVD adapters, Black PVD buckle, two 16mm spring bars, two 22mm spring bars (Standard, Army Green) :
PSA (YMMV) Amazon Warehouse GW-M5610-1 (GW-M5610U) used like-new for $77 : r/gshock
Amazon.com: G-Shock by Casio Men's GWB5600SL-5 Green Digital Watch : Clothing, Shoes & Jewelry
Natural Poly Urethane Replacement Watch Band Strap for Casio Mens G-Shock DW-5900 DW-6100 DW-6695 DW-6900 G-6900 GW-M5610 DW-5600E GW-6900 (J1) | Amazon.com