The Poppers Booster Cap XTRM SNFFR Double Large from XTRM takes the use of poppers to a new level. You simply unscrew the original cap from the manufacturer and screw the booster cap onto the bottle. You will quickly feel the difference. Another advantage is that the booster cap protects your skin from irritation and burns, as there is no direct skin contact with the poppers. After use, be sure to reattach the original cap from the manufacturer to prevent leakage. Try out the booster cap and leave a product review on this page. The Large size is suitable for all square 25ml bottles from the manufacturer Lockerroom.