40-4040 IS A 40MM X 40MM METRIC 40 SERIES SQUARE T-SLOT PROFILE WITH FOUR OPEN T-SLOTS, ONE ON EACH 40MM FACE. THE PROFILE IS SMOOTH, WHICH MAKES IT RESISTANT TO DIRT AND DEBRIS BUILDUP WHILE ALSO BEING EASY TO CLEAN. THE 40-4040 PROFILE IS COMPATIBLE WITH ALL 40 SERIES FASTENERS. THIS PROFILE IS THE MOST HEAVY-DUTY IN THE 40-4040 PROFILE FAMILY AND LENDS ITSELF TO CLEAN ROOM APPLICATIONS, GUARDS, ENCLOSURES, OR WORKSTATIONS. THE FOUR OPEN T-SLOTS ENABLE ACCESS FROM ANY DIRECTION AND ARE USEFUL FOR MOUNTING ACCESSORIES.,