The revolutionary Speed-Feed 400 takes the hassle out of refilling your trimmer head, and is the easiest tap-to-advance head available on the market today. The unique design allows you to reload in under 30 seconds in just 3 easy steps, all without disassembling the head, to save you time and get you back on the job faster. Genuine Shindaiwa replacement part. Speed-Feed Head 400 Clamshell. The Speed-Feed 400 is universal and includes adapters for use on both straight shaft and curved shaft models. Can be reloaded without disassembly in 30 seconds or less. Professional tap-to-advance line feed mechanism.