Starrett 657AA Magnetic Base Indicator Holder Complete Set with Attachments A/B/C/D/E/F

The Starrett 657AA is a complete magnetic base indicator holder set designed for use with all Starrett test, back-plunger, AGD, dial, and miniature-dial indicators. It also accommodates similar indicators from other manufacturers, making it a highly versatile tool for precision measurement in machining, inspection, and metalworking applications.

At the heart of the set is the 657P Magnetic Base, measuring 1-15/16" x 1-5/8" x 1-7/8" (50 x 40 x 48mm). The base features three precision-ground magnetic contact points and a V-step that allows it to grip horizontally, vertically, and upside down on steel or iron surfaces, as well as to arbors and shafts. A convenient push-button on/off switch enables one-handed operation, and an extra 1/4-20 tapped hole on one side provides a mounting point for the post. Non-working surfaces feature a durable black wrinkle finish.

What's Included (Attachments A through F):

• 657P Magnetic Base (A) — 1-15/16" x 1-5/8" x 1-7/8" with push-button on/off and three precision-ground contact points
• 657G Upright Base Post (B) — 3/8" (9.5mm) diameter x 7-7/16" (190mm) overall length; compatible with Starrett 57S and 58S Universal Snugs
• 657S Snug (C) — Two 1/4" (6.3mm) diameter holes; adapts 196, 650, and 651 Series Dial Indicators and 657Y Indicator Attachment to the 657X Rod
• 657X Rod (D) — 1/4" (6.3mm) diameter x 6" (150mm) long; accommodates Starrett 708, 709, 811, and 711F Series Dial Test Indicators
• 657Y Indicator Attachment (E) — 1/4" (6.3mm) O.D. on one end; opposite end threaded to fit lug backs of all AGD indicators (Starrett Series 81, 25, 655, 656) and Series 80 Miniature Indicators
• PT18724 Snug (F) — 3/8" (9.5mm) diameter post hole with 1/4" (6.3mm) diameter gripping hole to accommodate the 657X Rod

Key Features:

• Compatible with all Starrett test, back-plunger, AGD, dial, and miniature-dial indicators
• Also fits similar indicators from other manufacturers
• Three precision-ground magnetic contact points for secure, stable positioning
• Push-button on/off switch for one-handed operation
• Grips horizontally, vertically, and upside down on steel or iron surfaces
• V-step holds base securely to arbors, shafts, and similar profiles
• 1/4-20 tapped side hole for post mounting
• Tool steel construction with black oxide finish
• Includes all six attachments (A through F) as a complete set

The Starrett 657AA is sold as a complete set including the magnetic base and all attachments. Individual components are also available separately under their respective catalog numbers (657P, 657G, 657S, 657X, 657Y, PT18724). Starrett No. 57S and 58S Universal Snugs are also compatible with the 657G upright post and are sold separately.