You're confusing LP/LPX chain with Low Profile. 3/8LP chain (90PX/PXL, 91VX/VXL) is for small saws. The 70 series chain is standard size 3/8 pitch. The 70 series has 72/73/75 sizes for .060/.058/.063 gauges. Most of each of those sizes has different geometries/chassis like LP/LPX, LG/LGX, CL...