Artie with his bag.

Artie's bag5
Artie keeps this bag with him at all times, stocked with handy artifacts such as:

There are also several items used to neutralize artifacts or block artifact effects, such as specially designed earplugs, nasal spray, and a neutralizer aerosol spray. He also seems to keep at least one seemingly plain tennis ball in this, which he used to set off a chameleon mine in Time Will Tell. Also, he is seen to have a ping-pong paddle and a seemingly-ordinary brass compass in his bag when H.G. and Myka look through Artie's bag in Vendetta.

The bag itself is an artifact, confirmed by Jack Kenny in the DVD commentary for the season three episode "The 40th Floor". It's exact effects, besides always seeming to have something useful, are unknown, as are it's exact origins. Some have speculated it to be Mary Poppin's Bag, however that bag was made of carpet, whereas Artie's bag is leather and has two front pockets. A more likely speculation is that it is the original 'Bag of Tricks.' Artie himself seems to view it much like a doctor's black bag, providing not only the materials required, but also functioning as a tangible reminder that he is trained for, and can handle, this, whatever "this" might happen to be this time. Pete has commented on the fact that it always seems to have exactly what Artie needs, but Artie shushed him before he could finish, saying not to jinx it.