The Snap-on Heavy Duty Belt Tensioner Release Tool, No. SRD6, works on serpentine belt tensioners with a 1/2-inch square drive opening found on Series 60 Detroit Diesel and Caterpillar engines; Chrysler / Dodge 2.0L and 3.0L engines; Ford / Lincoln / Mercury 2.3L, 3.0L, 4.2L and 4.6L engines; and GM 2.5L, 4.7L, 5.0L and 5.7L engines. Due to the tool's low profile, it works well with sockets in automotive applications where a wrench or ratchet might not fit.