IF YOU LIKE TAKEING SEVERAL DIFFERENT KINDS, TRY EMPTY BIC INK PENS. .22 AND .25 CALS STACK PERFECTLY ON TOP OF EACH OTHER. A DOZEN OR SO PER PEN. EASY TO TUCK SEVERAL PENS UNDER A SWEAT BAND OR AMMO SLOTS ON A BUTSTOCK COVER, OR USE A PENS THAT HAVE SHIRT CLIPS.