Oster Master Flat Top Comb for the Oster 1-2-3 System. The Oster 1-2-3 system was developed to increase efficiency. To compliment the ""clipper over comb"" technique, Oster created the 1-2-3 flat combs. The Master Flat Top Comb is strong, yet flexible, virtually unbreakable, heat resistant, chemical resistant, friction resistant, static free, sterilizier compatible, long lasting, and flat not bulky.