If you damaged your screen or would just like to have a spare around this is the replacement screen for the USFS approved spark arrestor end cap insert ST-3.
Part# RP-S-30 Technical Data:
PAETENT PENDING & USFS APPROVED (REF. FILE#0880-01)
USFS approved replacement screen for ST-3
Screen-stainless steel
Weight- 3 grams/0.1 oz