Porter Cable 42950 1/2" Router Collet:Porter Cable 42950 Specifications:  Shank: 1/2"  Compatibility: 690, 9690, 691,693, 693PK, 7529, 97529, 7518, 7519, 7538, 7539 Porter Cable 42950 Features:  1/2" Router collet for use as a replacement or adapter  Auto-release design prevents "frozen" bits  Accepts 1/2" shank router bitsPorter Cable 42999 1/4" Router Collet:Porter Cable 42999 Specifications:  Size: 1/4"  Compatibility: 690, 690LR, 9690LR, 691, 693, 890, 891, 892, 893