Self tapping screws with 3mm Allen key head.The Head is 7mm Dia x 4mm High.The Shaft is 4mm Dia x 20mm Long.
A suitable driver bit can be found Here.
Price is for a bag of 20 screws.
SpeakerBug is an Australian home based business dedicated to providing high quality parts for D.I.Y. speaker construction and upgrades at affordable prices.