The Spectools Box Wrench Power Conversion Attachment Set converts either 1/4" or 3/8" drive mini head air or cordless ratchet to low profile box wrench output. 1/4" to 3/8" drive adapter included. The head fits most 1/4" and 3/8" power ratchets with round necks up to 1" diameter with 1-1/2" min length. This set increases drive input torque by up to 30 percent, with 40 lb-in max input, the company says. The slim 1/2" thick profile is designed into fit into narrow and hard to reach areas.