Dimensions:
OD: 21mm, ø: 3mm - NBR Type - Blow moulded w/ seam line.

Please note that this item is not a UMAREX original / factory product but has instead, been locally manufactured.

This seal is a replacement for the green one that circles the bump cap assembly. Please do note that the factory standard green one sits inside of a groove, beyond a series of small pitch, sharp threads. We ABSOLUTELY cannot recommend the use of a set of o-ring picks enough. Please don't roll the O-ring over the threads with your hands - there is a high likelihood of the O-ring ending up incorrectly installed and likewise, its service life shortened. Also have some silicone grease handy, for the threads, to make your life easier. The grease you can leave on afterwards, as they will lessen the inter-thread friction, each time you thread the bump cap assembly back into the marker.

Be sure to keep your O-rings in general lubricated and especially prior to installation, to assist with pliability, which makes installation easier.

You can use common mineral oil to lubricate your O-rings;

• SINGER ALL PURPOSE OIL - 80ML

The symptom of this O-ring being faulty, is due to a leak out the bottom, once your T4E marker has been pressurized. We normally recommend trying to leave your green O-ring in a solution of silicone oil for 24 hours. This might sometimes rejuvenate the O-ring and make it functional again. But in other cases, excessive exposure to low temperatures might cause the O-ring to irreversibly shrink or become hard. In these cases unfortunately, a replacement is necesitated. As such, we don't recommend that you keep your T4E marker perpetually pressurized - These markers were designed w/ a bump cap / stand by feature, so as to avoid keeping CO2 pressure on your O-rings. We'll stress the necessity of lubrication again.