OD size: 20mm (approximately size of a penny) Liquid filled, works under sub-freezing temperatures. Easy to read compass dial sealed with clear acrylic top and black plastic base. Grooved edge for easy carrying with a lanyard.. Each compass weight only 0.08oz.. This listing is for 2 dozen (24pcs) new liquid filled mini button compasses. These well-made mini compasses are perfect for use in compact, mini, or pocket survival kits. Or put them onto your walking stick, knife, binoculars, backpack, Paracord Bracelet, etc.