Description. Description. Insert part numbers that are compatible with these large opening vials: 29435-U PK100, Certified 200 muL glass inserts, mandrel precision point, 6 X 29 mm, with bottom spring. 29436-U PK100, Certified 250 muL glass insert, conical bottom, 6 x 31 mm. 29437-U PK100, Certified 300 muL glass inserts, conical bottom, 6 x 30 mm. 29441-U PK100, Certified 350 muL glass inserts, flat bottom, 6 x 31 mm.