This is a 28" chainsaw guide bar.  3/8" pitch, .050 gauge, 93 drive links.

Replaces part number 280RNDD009.

Fit Husqvarna: 1100 CD, 160, 162, 181, 185, 2100 CD, 2101, 266 XP, 268, 272 XP, 281, 285, 288 XP, 298, 3120 XP, 362 (9mm Studs), 365, 371 XP, 372 XP, 380, 385 XP, 390 XP, 394 XP, 395 XP, 465 Rancher, 480 CD, 562 XP, 565, 570, 572 XP, 575 XP, 576 XP, 61, 65, 66, 70, 77.  Fits Dolmar:  PS-6400, PS-6400 H, PS-6400 W, PS-7300, PS-7300 H, PS-7300 W, PS-7310, PS-7300 H, PS-7310 W, PS-7900, PS-7900 H, PS-7900 W, PS-7910, 
PS-7910 H, PS-7910 W, PS-9000, PS-9010, PS-9010F.   Fits Echo:  CS-7310P, CS-7310PW  Fits Jonsered: 2065, 2071, 2077, 2083, 2094, 2095, 2165, 2171, 2186, 625, 630, 670, 
CS 2165, CS 2166, CS 2171, CS 2172, CS 2186, CS 2188.  Fits Makita: DCS 6400, DCS6401, DCS 6420, DCS 6421, DCS6800, DCS7300, DCS7301, DCS 7900, DCS7901, DCS9000, DCS9010FL
Fits Partner: 1655, 2055, 550, 650, 7000, P-100, P-55, P-65, P-70, P-85, R-11, R-12, R-14, R-16, R-17, R-18, R-19, R-20, R-21, R-22, R-23, R-30, R-35, R-40, R-416, R-420, R-421, R-435, R-440, S-50, S-55, S-65
Fits Poulan/Poulan PRO: 415, 425, 445, 475, 505, PRO415
Fits RedMax: GZ7000, GZ7100, GZ9000
Fits Shindaiwa: 550, 575, 577, 680, 695, 757, 757C, 757W
Fits Solo: 603, 662, 665, 667, 670, 675, 680, 681, 690, 694
Will not fit the old Jonsered models like 621, 70E, 820, 920 that have 10mm bars studs.